2021 West Texas Insect Collecting Trip iReport

Alternative title: Rich and Ted’s “Excellenter” Adventure.

This is the ninth “Collecting Trip iReport”; this one covering a 10-day trip to western Texas from April 27 to May 6, 2021 with friend and local collecting buddy Rich Thoma. Rich and I have done many shorter collecting trips (up to five days) throughout Missouri and in the neighboring states of Kansas, Nebraska, and Oklahoma (in fact, our first joint trip was to Barber County, Kansas way back in May 1986!). This trip, however, was our first truly long one together—10 days of collecting plus a travel day on each end. To take full advantage of the amount of time we had, we chose western Texas; an area that I have visited several times from the mid-90s through 2004 but not since. We wanted to make the trip during early to mid-May, but scheduling conflicts forced us to go earlier. I reasoned that even if it was a bit too early in the season, I could still collect infested wood for rearing—as I did with great success during my April 2004 trip. For Rich, who is more of a general insect collector, the trip provided him an opportunity for extended collecting in an area that he’d not previously spent a lot of time.

As with all previous “iReports” in this series, this report is illustrated exclusively with iPhone photographs (thus the term “iReport”), with previous versions including the following:
2013 Oklahoma
2013 Great Basin
2014 Great Plains
2015 Texas
2018 New Mexico/Texas
2018 Arizona
2019 Arkansas/Oklahoma
2019 Arizona/California


Day 1 – Monahans State Park, Shin Oak Picnic Area
First stop of the trip. I was hoping to see beetles on flowers and maybe some tiger beetles, but unfortunately the area hasn’t had any rain yet this spring (according to the ranger). The mesquite was in bloom, but the only beetles I beat from it were a few tiny weevils. A few other plants were in bloom, but only one—Hymenopappus flavescens—had beetles on it (mordellids, which I picked up for Enrico Ruzzier). After a lot of walking I noticed Quercus havardii (shin oak) with flagged branches of dead leaves—a bit of investigation revealed it had been attacked by what must be Chrysobothris mescalero, so I collected as many flagged branches as I could find (7 total) and will bring them back for rearing.

Monahans Sandhills State Park.
Oenethera berlandieri (Berlandier’s sundrops).
Penstemon buckleyi (Buckley’s beardtongue).
Hymenopappus flavescens (collegeflower)—host flower for mordellids).
Chaetopappa ericoides (rose-heath).
Quercus havardii (shin oak) attacked by buprestid, presumably Chrysobothris mescalero.

Monahans State Park, Sandhills Picnic Area
The big dunes are in this area. We didn’t expect to see any insects but brought our nets anyway. As we were walking the ridge we saw two grouse-like birds in the distance. We tracked them for a bit before I decided to go back and get my binoculars. They kept us at bay, but eventually I was able to get close enough to get a good look at them—they turned out to be scaled quail, a new bird for me. We continued tracking them and eventually they were joined by two more individuals. Handsome birds!

Rich scans the vast sand dunes.
Endless dunes!

Monahans State Park, Shin Oak Picnic Area
After going into town and picking up some dinner, we came back out to the park and setup the ultraviolet lights. I didn’t have much optimism based on the lack of insect activity we saw during the day, but the temperatures were still plenty warm (well into the 80s) and we had nothing better to do. We returned to the Shin Oak Picnic Area since it had a mix of open and more vegetated dunes. Glad we did because two male Prionus arenarius, one Megacyllene antennata, and a tiny, unidentified elaphidiine came to the lights. I also found two small darkling beetles crawling on the sand nearby. I searched the surrounding sand hoping to find more males looking for females, or perhaps even a female herself, but found none. Wolf spiders, however, were common on the sand, their glowing eyes drawing attention beyond their abundance. I guess they are a species of Hogna, but I’m not certain—I photographed two individuals. Also got a large bostrichid (Apatides fortis?) at the light. Before we took down the lights, Rich called me over to see a tiny, slender, worm-like snake that we eventually determined was one of the blind snakes (Leptotyphlum sp.)—definitely a first for me.

Blacklights setup and humming.
Prionus arenarius male in front of the blacklight. This species is restricted to sand dune systems in west Texas and southeastern New Mexico.
Megacyllene antennata at ultraviolet light.
Hogna sp. (burrow-living wolf spider)—individual #1. This one appears to be a large female.
Hogna sp. (burrow-living wolf spider)—individual #2.
Hogna sp. (burrow-living wolf spider)—individual #2.

Day 2 – Toyahyale
We stopped here on a tip from Jason Hansen and Tyler Hedlund, who swept good numbers of Agrilus cochisei off of Ambrosia psilostachya (western ragweed)—albeit, a few weeks later during May. I found the plants, but they were very small and low to the ground. Nevertheless, adults could be swept abundantly from the plants, and I was able to take good photos of singles and a mating pair with the big camera (iPhone photo here just to show what they loook like). Also got a single specimen of an apparently undescribed Acmaeodera sp. while sweeping for A. cochisei and one of two A. cochisei adults that I saw on flowers of Sphaeralcea sp.

Ambrosia psilostachya (western ragweed).
Agrilus cochesei mating pair on Ambrosia psilostachya (western ragweed).

Davis Mountains, 15.8 mi NE Ft. Davis
We stopped here to look for the undescribed species of Acmaeodera, which Jason had found in good numbers during May on blooms of Lygodesmia and Convolvulus. Both plants were present, but neither was in bloom. Still, I found one adult on flowers of Verbina sp. and swept another from roadside vegetation. Ambrosia polystachia (western ragweed) was also present—I looked visually for Agrilus cochisei and did not see any, but I did get one adult and a couple of cryptocephalines in the sweeping that produced the second Acmaeodera.

Verbina sp. (host for Acmaeodera sp.).
Verbina sp. (host for Acmaeodera sp.).

Day 3 – Point of Rocks Roadside Park
The weather turned decidedly cool in the Davis Mountains—first time I’ve ever frozen camping out on a collecting trip. The high temps are expected to stay in the 50s to 60s with a chance of rain for the next few days, so we decided to head down to the Big Bend area where there is still a chance of rain but warmer temps (up to the high 70s). Maybe we’ll come back to this area next week. Before leaving, however, I wanted to check the Quercus vasseyana (vassey oak) at Point of Rocks, where in the past I collected a good series of Mastogenius texanus even earlier in April (it was actually undescribed at the time). I’ve also collected Elytroleptus lycid-mimicking cerambycids on soapberry flowers here in June, although I knew the soapberry would not be in bloom. There was nothing on the oaks, but I did collect a few miscellaneous beetles beating Prosopis glandulosa (mesquite) and found one vassey oak branch with evidence of wood-boring beetle larval feeding and which I collected for rearing.

Point of Rocks Roadside Park.

17 mi S Alpine
This is the first of two picnic areas along Hwy 118 going south from Alpine towards Big Bend National Park. There are lots of big Quercus vasseyana and Q. grisea here, so I stopped to see if I could find any infested wood. Bingo—one of the Q. grisea had a dead branch hanging from it that looked recently dead, and breaking apart a few of its smaller branches revealed fresh larval workings of some kind of buprestid (perhaps Polycesta arizonica). I cut of the branch and will bring back the bundle for rearing.

Dead Quercus grisea (gray oak) cut and bundled for rearing.

26 mi S Alpine
This is the second of two picnic areas south of Alpine on Hwy 118 towards Big Bend National Park. Rich and I have both stopped here before, and Rich brought back infested wood (apparently Juglans sp.) from which I reared Chrysobothris comanche, so that was the plan again unless we saw active insects. We did not, so I scanned the trees and found a small Celtis laevigata (sugarberry) that had recently died—the bark was peeling, but there were no emergence holes that I could see. I started chopping into the trunk wood and quickly encountered a large buprestid larvae in its “pre-pupal fold”. This could be Texania fulleri based on host and location, so I cut a couple of bolts from the trunk to bring back for rearing. The branches also showed fresh larval workings, so I cut up one along with its smaller branchlets to also bring back for rearing.

Texania sp. prob. fulleri larva in trunk sapwood of dead Celtis laevigata (sugarberry).

3.3 mi W of Hwy 118 on Agua Fria Rd.
Last stop of the day, which I was told could have water with tiger beetles. The creekbed was bone dry, and I collected but a single Chrysobothris sp. beating Prosopis glandulosa in flower—amazing given the proliferation of wildflowers that were in bloom. We did find a nautiloid/ammonite-type fossil in the bone-dry creekbed, which Rich says is of Cretaceous origin based on clam fossils in the underlying layer, and I tracked a common poorwill (Phalaenoptilus nuttallii) for a little bit, eventually getting close enough for the rare iPhone bird photo. Interesting position it assumed upon landing with its wings outstretched above its back.

Amazing wildflower displays in the area.
Seam in sedimentary layer of bedrock. I’m not sure if it is of volcanic provenance.
Nautiloid/ammonite-type fossil—large (about 8” diameter).
Common poorwill (Phalaenoptilus nuttallii) feigning injury.

Big Bend Ranch State Park, West Contrabondo Campground
We arrived in Study Butte with just enough time to check into a motel and get dinner before heading out to Big Bend Ranch State Park. The drive through the park was incredible as we searched for a spot to setup the lights. After finding such spot, however, we were greeted as we got out of the car by a stiff, chilly wind. I knew there was no point in going through the trouble to setup, so instead we drove further down the 2-track to an amazing scenic overlook into an impressive box canyon. Words cannot describe the contortions this acrophobiac took to find good position for these photos, but it was well worth the views.

Dusk along Hwy 170 approaching Big Bend Ranch State Park.
Sunset over canyon near West Contrabondo Campground.
The closest I will ever get to the edge of a canyon!

Day 4 – Big Bend National Park, Boquillas Canyon Trail
Well, the rain and cold continue to follow us. Rather than trying once again to drive somewhere else to escape, we decided to just sit this day out and visit the national park (not a bad Plan B!). Boquillas Canyon is an amazing slice through the rocks along the course of the Rio Grande River, and we hiked as far into the canyon as we could before sheet rock on the left and deep water on the right prevented any further progress. We saw only two insects—a tiger beetle larva that I “fished” out of one of the many larval burrows we saw (definitely Tetracha, and likely T. carolina) and a velvet ant (black head and pronotum, red abdomen).

Rio Grande River from Boquillas Canyon Trail.
Tetracha sp. prob. carolina (Carolina metallic tiger beetle) larva extracted from its borrow.
Mouth of Boquillas Canyon.
Mouth of Boquillas Canyon.
Cobblestone view of Boquillas Canyon.
Rio Grande River in Boquillas Canyon.
Rich contemplates emigration.
Still contemplating.

Big Bend National Park, near Panther Junction
Driving towards the Chisos Mountains after hiking the Boquillas Canyon Trail, we encountered this fine adult male Aphonopelmis hentzii (Texas tarantula) crossing the road.

Male Aphonopelmis hentzii (Texas tarantula).

Big Bend National Park, Chisos Basin, Window Trail
After lunching at Panther Junction, we headed up the into the Chisos Mountains towards Chisos Basin. Heavy clouds shrouded the peaks, so we weren’t sure what we would encounter up there, and once in the cloud zone and then heading down into the basin we could hardly see anything. Suddenly the western side of the basin came into view, still overcast and drizzly but at least free from the heavy fog that shrouded the eastern half of the basin. That made our decision of which trail to hike easy—the Lost Mines Trail under heavy fog versus the Window Trail with semi-clear views. I’ve hiked the Window Trail several times, but the last time was 17 years ago, and Rich in his single attempt a year or two later did not make it to the “Window” due to an impatient 10-year old son in tow. The views on the way down the canyon were spectacular—not despite the rain and clouds but because of it. It is a rare opportunity to see richly moist desert mountains shrouded in mist. At one point on the way down, a Woodhouse’s scrub jay (Aphelocoma woodhouseii) caught our attention—sitting very nearby in a tree before hopping down to the ground and nonchalantly pecking for bugs. Another soon joined him, first landing on a branch just a few feet above me and returning my captivated stare for a few moments before joining his mate on the trail ahead of us… followed shortly by a third individual. Their soft chirpings were a charming contrast to their more familiar raucous calls, and Rich and I soaked in the moment until they moved on. The trail is not an easy hike—nearly 7 miles round trip, dropping over a thousand feet on the way down, and then gaining over a thousand feet on the way back. The “Window,” however, is a sight to behold—a narrow gap in the rocks soaring high overhead with a view out onto the desert floor almost a thousand feet below. There is tempting danger at the window—its smooth, water-carved rocks are deceptively slippery even in dry conditions, and with the rain of the day they were especially so. I would not be surprised to learn that at least one person had made a fatal error in judging how close to the window one can get. They would have had plenty of time to think about that mistake on the way down! The views on the way back up were even more breathtaking, as fog enshrouded the high peaks towering above us. Periodically the sun attempted to push through the clouds, creating surreal lighting in a battle of sun versus rain, but eventually the rain won out and fell steadily on us for the last, switchback-laden mile back to the trailhead. As for insects, we actually did see some despite the rain—a few blister beetles resting torpidly on yellow composite flowers.

Window Trailhead.
Chisos Mountains’ South Rim from Window Trail.
Chisos Mountains east rim from Window Trail.
Beginning the descent to the “Window.”
Rich photographs a Woodhouse’s scrub-jay.
Yellow composites bloom en masse.
Resting point halfway down—Rich’s prior turnaround point.
The descent steepens!
Steps carved into the rock aid the traverse across slippery rocks.
The “Window” from as close as I was willing.
The author (left) and Rich document their arrival at the “Window.”
Looking back at the “Window” from a bit further back up the trail.
Beginning the rugged, 1,000-ft ascent back up to the basin.
Clouds and mist shroud the surrounding peaks.
A rainy last few miles provides a spectacular last look at from whence we came.

Day 5 – Big Bend National Park, Sotol Overlook
We’re on our way to Santa Elena Canyon and stopped at this overlook. From a distance of 14 air miles, the canyon entrance looks like a tiny split in the rocks, belying the 1000-foot canyon walls that await us. Cacti were nicely in bloom, if a bit rain battered—two species of yellow-flowered Opuntia (pricklypear) and the always extraordinary pink flowers of Cylindropuntia imbricata (tree cholla). No insects were to be found, but we did find a live Orthoporus ornatus (desert millipede)—the first that we’ve seen on this trip—who obliged us by coiling into its classic defensive pose.

View towards Santa Elena Canyon—some 15 miles to the south—from Sotol Vista Overlook.
Orthoporus ornatus (desert millipede).
Cylindropuntia imbricata (tree cholla).

Big Bend National Park, Santa Elena Canyon
From 14 air miles away, Santa Elena Canyon looks like a tiny split in a little cliff (see previous post). Up close, however, it’s soaring walls tower 1000 feet overhead! The hike into the canyon features a tortuous staircase to bypass a narrows, followed by a leisurely stroll along the canyon bottoms along the Rio Grande River. Rain last night has triggered an en masse millipede emergence, and even a few insects were seen: velvet ant; Acmaeodera mixta, Trichodes sp. and Gnathium sp. on yellow composite flowers; and Omorgus sp. crawling in the sand.

Undetermined yellow composite in Rio Grande River floodplain.
Euodynerus pratensis on flower of undetermined yellow composite.
Mouth of Santa Elena Canyon.
The Rio Grande River spills forth from Santa Elena Canyon.
Agave lechuguilla (lechuguilla).
View of Mexican side of Santa Elena Canyon from the U.S. side.
The Santa Elena Canyon Trail probes deeper into the canyon.
Narrowing canyon walls.
No more land!

Big Bend National Park, Cerro Castellan (Castolon Peak)
The layers visible in Cerro Castellan reveal millions of years of volcanic events. Stacked in this tower are several lava flows and volcanic tuffs (ash deposits), with layers of gravel and clay from periods of erosion between eruptions. Cerro Castellan’s cap rock is the same lava that formed the Chisos’ South Rim. The lighter orange and gray layers beneath are tuffs.

Cerro Castellan (Castolon Peak).
A smaller peak northwest of Cerro Castellan rises above volcanic tuffs (ash deposits) in the foreground.
Cerro Castellan (Castolon Peak).

Big Bend National Park, Tuff Canyon Trail
Some of the oldest layers of volcanic rocks lie at the bottom of Tuff Canyon. It is dry most of the time, but summer thunderstorm runoff churns through the canyon, cutting it deeper. This canyon is narrower and deeper than most others in Big Bend, partly because the light gray volcanic tuff is relatively cohesive. Swift, powerful floodwaters will cut down through any kind of bedrock, but the tuff is better able to resist the widening effects of sideward erosion.

Looking down into Tuff Canyon.
Northern branch of Tuff Canyon.
Northern branch of Tuff Canyon.
Southern branch of Tuff Canyon.
Fouquieria splendens (ocotillo).
Entering the south end.
Chilopsis linearis (desert willow).
Rich entering the southern end of the canyon.
Deeper into the canyon.
Deeper still.
Eucnide bartonioides (rock nettle, yellow stingbush).
Eucnide bartonioides (rock nettle, yellow stingbush).
Cairns (not a natural feature).

4.6 mi W of Langtry
After leaving Big Bend National Park we started making our way towards the Del Rio area in Val Verde Co., where we plan to meet up tomorrow with a few other beetle collectors (Dan Heffern, Brian Raber, and Ed Riley). I noted that our path took us right by the type locality of the recently described tiger beetle, Amblycheila katzi. I didn’t have much hope of actually seeing the species, given that the season seems to have even really started yet and the earliest record of the species is the 23rd of May. Nevertheless, since we happened by the spot right as dusk was falling it seems a good idea to at least try. First we walked the limestone 2-track just to see what was out and about (just a few darkling beetles), then we started checking the limestone ledges where the tiger beetle can be found. We checked about 100 m of ledge without seeing any, and I was about ready to call it a night when we finally spotted one. It was running in a seam about 2 m above the ground and was unmistakable. My attempt tiger an in situ photo failed at first, and it almost escaped deep into a crevice before I pulled out my long forceps and pulled him out by a tarsus. It gave me a healthy pinch when I grabbed it while fumbling in my pack for a bottle, but eventually I prevailed. Later on I placed it back on the ledge and covered it with the Nalgene bottle cap, waited for it to calm down, then carefully lifted the cap and got a couple of shots before it began scurrying again. We checked another 50 m of ledge without seeing any and decided to call it a night.

Rich scanning the ground at dusk for nocturnal insects.
A wolf spider in the subfamily Lycosinae.
Amblycheila katzi (Trans-Pecos giant tiger beetle).
Amblycheila katzi (Trans-Pecos giant tiger beetle).
Selenops actophilus, one of the so-called “flatties.”

Day 6 – Comstock (prologue)
The owner of the motel in which we stayed was super friendly and kind enough to leave a key in the door for our very late arrival last night. Settling up this morning, I saw this on the wall (right next to his vaccination card—two doses) and just had to get a pic. He was only too happy to oblige when I told him how awesome it was and could I get a picture. Hey, no reason to reveal true political leanings if it means we can all just get along.

Trump Lost LOL!
Illegal tender.

Amistad National Recreation Area, Spur 406 Campground
A quick stop here on the way to meet up with Dan, Brian, and Ed near Devil’s River. There were lots of dead and dying Acacia constricta (whitethorn acacias), off of which I beat a diversity of cerambycids and buprestids from both the dead and dying branches. I found one small sapling of the same with evidence of fresh woodboring beetle larval feeding, so I collected it as well for rearing. Other than that I just collected a few weevils off of living Prosopis glandulosa (mesquite) for weevil-specialist Bob Anderson.

Apiomerus spissipes, one of the bee assassins, in flower of Opuntia engelmannii (Engelmann’s pricklypear)

Devils River near Dry Devils River
We met up with Dan, Brian, and Ed north of Del Rio and, after exchanging peasantries, followed them into a private resort surrounding a stretch of the Devils River*—considered by some to be the most unspoiled river in Texas. Dan had arranged for access after befriending Dave Barker, a commercial herpetologist who had built a home on property overlooking the Devils River and also a guest cabin on property overlooking nearby Gold Mine Canyon. We met up at the cabin and then carpooled to a spot along the Devils River where Dan and Brian had placed a variety of traps that needed servicing. While they took care of that, Rich, Ed, and I collected in the area around where the traps had been placed. I started off beating dead branches of Vachellia farnesiana (huisache), sweeping blooming Salvia sp. (sage), and beating dead branches of Acacia rigidula (blackbrush acacia) down by the river but collected only a smattering of beetles. I then clambered up the rocks and found good numbers of Acmaeodera spp. visiting flowers of Echinocereus enneacanthus (strawberry cactus) and Opuntia engelmannii (Engelmann’s pricklypear). After collecting my fill of those beetles, I returned to the riverbanks and noticed some large Carya illinoensis (pecan), from which I beat a few Anthaxia (Haplanthaxia) sp. (hoping they are one of the recently described taxa). By then, Dan and Brian had finished servicing their traps and gave me a few specimens that had been collected in their ethanol-baited Lingren funnel trap.

* The accepted usage of the name is without an apostrophe, although the reason for this is a matter of debate.

Dan (right) and Brian service a malaise trap.
Echinocereus enneacanthus (strawberry cactus).

After finishing along the Devils River, Dave invited us to his home for a few post-collecting beers. Spectacular views overlooking the river.

The author (left) with (L-R): Dan Heffern, Brian Raber, Dave Barker, Rich Thoma, and Ed Riley.

Gold Mine Canyon
We setup a variety of light stations at Dave’s cabin a little east of the river. It was warm and dry, so conditions were good, if a bit windy. My two ultraviolet light stations a bit north of the cabin ended up catching the lion’s share of cerambycids, although it was mostly elaphidiines and a Lepturges sp. We also picked up a few tenebrionids and a Carabidae crawling on the ground near the lights. Ed’s mercury vapor/ ultraviolet station on the road west of the cabin attracted a few more cerambycids, including a Lagocheirus sp. Dan, however, got the catch of the night—a Goes that came to Dan’s $6 battery-powered lantern on the road south of Ed’s station. We at first thought it might be G. novus, but that Dan later decided it was just a very lightly marked G. tesselatus. Zephyranthes chlorosolen (Brazos rain lily) blossoms were beautiful at night, their stark whiteness catching the beam of the headlamp.

Zephyranthes chlorosolen (Brazos rain lily).

Day 7 – Gold Mine Canyon
Rich and I spent the morning walking the grounds around Dave’s cabin while the others packed up and got ready to leave. I found some oak (Quercus vasseyana) saplings infested with cerambycid larvae, which I cut and bundled to bring back for rearing. Acmaeodera were already coming to the flowers—a couple of small ones on an undetermined white composite, three different species on Opuntia engelmannii (Engelmann’s pricklypear) and Echinocereus enneacanthus (strawberry cactus) flowers, and a couple on Coreopsis? flowers. I beat some of the Diospyros texana (Texas persimmon) looking for Spectralia robusta but did not find any. It got hotter than blazes real quick!

Opuntia engelmannii (Engelmann’s pricklypear).

After Dan, Brian, and Ed left, Rich and I went down to the canyon entrance to beat on the oaks and Texas persimmons that dot the sides of the canyon. Nothing was on either plant, however, and I ended up again concentrating on the diversity of Acmaeodera that were coming to flowers of Coreopsis sp., Opuntia engelmannii, and an unidentified yellow composite. I did beat a single Cleridae off a dead branch of mesquite.

Gold Mine Canyon.

Devils River near Dry Devils River
After finishing at Gold Mine Canyon, we came back to the Devils River crossing near the first stop we made here for our final stop of the day. Temperatures had maxed out at 99°F! and I wasn’t too motivated to collect much more today, but when we arrived at the spot I noticed some declining Platanus occidentalis (American sycamore) with large emergence holes suggestive of Mallodon dasystomus and old fallen branches with the same suggestive of Polycesta elata. The tree with the Mallodon holes was much too large to cut (and embedded within a thicket of poison ivy), so I occupied myself by collecting a few more Acmaeodera off of Opuntia engelmannii flowers. As I walked the roadway I noticed more sycamore with some smaller trees in the grove that looked recently dead. One was dead from about three feet up and had buprestid workings under loose, peeling bark. I cut just above the live portion (3–4” diameter) and took three 4-ft sections of the trunk above that point, each cut showing internal galleries. If P. elata emerges from these pieces of wood I will be “elated” [Later edit: I did rear the species!].

Devils River crossing.
The water was too deep for my Ford Escape.
Next time I’ll have a higher-clearance vehicle.

Gold Mine Canyon
For blacklighting tonight we decided to bring the lights down to the mouth of the canyon where we collected this afternoon so we could have acces to anything associated with the oaks. Unfortunately it was a much slower night than last night and cooled off quickly despite the high heat earlier in the day. I only got three cerambycids (one Ecyrus and two Aneflomorpha) and a few clerids at the lights. I also walked the jeep track leading to the mouth of the canyon and the main road outside and didn’t see anything until I almost got back, when I noticed a beetle sitting on the trail that looked a bit odd. When I picked it up I realized it was a buprestid in the genus Melanophila—what the heck?! Totally unexpected to see this beetle at night and especially on the ground instead of on a tree. I suppose it is one of the juniper-feeding species (since pine doesn’t occur here).

Sinking sun over Gold Mine Canyon.

Juniper cadaver in late-evening light.

Day 8 – Gold Mine Canyon
Our plan today was to head over to some spots further west in Val Verde Co., but before leaving the cabin we did a bit of walking around and took a last few photographs.

Gold Mine Canyon in the morning.
Epithelantha micromeris (button cactus).

22 mi N Del Rio
I had noted a few scattered plants of Senna roemeriana (two-leaved senna) at this spot a couple of days ago when meeting up with Dan but didn’t have the chance to sample them for Agrilus obtusus—one of my target species for the trip. I found one on the second plant I checked, so I went back to the truck to get my big camera hoping to photograph one in situ. I didn’t see anything on the next plant, but when I tapped it over my net there was another one! I did that for the next hour or so—inspecting and tapping—and never saw another one. Rich did get one sweeping the S. roemeriana (in an area I’d already worked) and was gracious enough to give it to me. There were also tiny bruchids and clerids on the plant. Other than that I got a couple of Acmaeodera mixta sweeping, a couple of Canthon sp. in flight, and a Euphoria kerni on the flower of Zephyranthes chlorosolen.

Senna roemeriana (two-leaved senna).

Hwy 90 at Del Rio River
I first visited this spot nearby 30 years ago based on a tip by Dan Heffern, who had reared a Polycesta elata from Fraxinus greggii (Gregg ash). I found the ash on that visit, though I didn’t find any wood infested with that species here, but what I did find was Diospyros texana (Texas persimmon) infested with Spectralia robusta and managed to rear out a few individuals. That was my quarry today, but when I arrived the abandoned road on the northwest side of the bridge was fenced and posted. I took a look on the southwest side and found open access up top and decided to hike down towards the ravine from that point. Things seems to be about as far along here as they were at Devils River, with not much activity except for Acmaeodera coming to the Opuntia engelmannii flowers, albeit not quite the diversity. I found a few more also on flowers of an undetermined yellow composite, Coreposis sp., and an undetermined white composite. Closer towards the ravine I found just a single large F. microphylla (with no signs of infestation) and several D. texana—two of which had the half-live/half-dead branches in which S. robusta larvae live and showing the emergence holes of adults. I collected both branches and will bring them back for rearing.

Hwy 90 bridge over Pecos River.
Adult emergence hole of Spectralia robusta in live/dead trunk of Diospyros texana (Texas persimmon).

Amistad National Recreation Area, Pecos River Access Nature Trail
Just a quick stop at the Pecos River Access on the east side to walk the short nature trail and gaze at the 300-ft high, 100 million-year-old (Cretaceous Period) limestone bluffs that the Pecos River has cut near the junction with the Rio Grande River (the latter can be seen on the left side of photo 2). The first photo also shows the old road that was originally used to cross the river snaking down the west bluff—traffic today uses the tall bridge in the right side of the photo.

Limestone bluffs over the Pecos River
Pecos River junction with the Rio Grande River.
Pecos River Access Nature Trail.

Seminole Canyon State Park, Canyon Rim Trail
We came here looking for oak potentially infested with Spectralia roburella. We didn’t find any oak on this trail, but I did find a Acacia rigidula (blackbrush acacia) showing signs of infestation by buprestid larvae (difficult to find such this year because the freeze in February apparently killed or severely knocked back most of this species). I cut up and bundled the wood to bring back for rearing.

To insects, the collectors’ shadows loom large.

Amistad National Recreation Area, Spur 406 Campground
We got to Seminole Canyon State Park too late to check with the supervisor about setting up our blacklights at the park, so we came back to Spur 406 Campground where we’d collected a few things two days earlier. Temps were okay and there was no moon or wind, but it was still a very slow night—for me just a couple of elaphidiines, two trogids, two Digitinthophagus gazella (why do I continue to pick these things up?), and a bostrichid.

Ready for another night of blacklighting.

Day 9 – Seminole Canyon State Park, Windmill Trail
We came back to the state park since we ran out of time to look for oak yesterday. The park staff were extraordinarily helpful—both in getting me checked in with my permit and in directing me to the spots where I might be able to find oak. Their first tip—along the Window Trail—paid off, where we found a nice cluster of Quercus fusiformis (plateau live oak) clinging to the upper canyon walls. Most of them had dead branches on them, and I did some beating to see if by some chance the beetles would be out already. They were not, but on the second tree that I examined I found a main branch from near the base with the outer 4–6 ft dead but the bark not peeling and small living sprouts about 2 ft from the base. Pulling apart the dead portion revealed buprestid larval workings, likely my quarry—Spectralia roburella, but these could be old. I cut the branch at the base, however, and found fresh larval galleries in the sapwood of the still-living portion even extending into the trunk—success! I’ll bring this back for rearing and will hopefully get S. roburella out of it. Further along the trail I found a single Senna roemeriana (two-leaved senna), inspected it carefully and didn’t see anything, then tapped the plant over my beating sheet and a single Agrilus obtusus fell onto it to add to the three that I got yesterday. I really wish I could see these things before I beat them off the plants so I could take an in situ photo!

The Maker of Peace, a bronze sculpture by Texas artist Bill Worrell.
View of Seminole Canyon to the east.
View of Seminole Canyon to the west. The Fate Bell rock shelter is on the right at the bend.
A vulture soars overhead.
Panoramic view of Seminole Canyon.
The author admires a fine stand of Quercus fusiformis (plateau live oak). No oaks were harmed in the making of this photo!😊
My souvenir for the trip!

Seminole Canyon State Park, Canyon Rim Trail
Another place the park staff recommended to find oaks was along the Canyon Rim Trail. We hiked that trail yesterday for a bit and didn’t see any oaks, but it turns out they were farther down the trail then we went. We headed back out on the trail to find them, along the way checking Opuntia engelmannii flowers for Acmaeodera and seeing only one for the time being. Just past the first of two east-facing ravines where we expected to find oaks, we found one on the canyon edge that looked rather bedraggled. There were some completely dead branches with bark already sloughed but also one large fresher-looking dead branch that had one live branchlet coming out of it about a third of the way up (meaning there was at least a strip of live wood within the branch). I broke of one of the dead branches near the live/dead junction, and there in its gallery was a smallish buprestid larva that almost certainly is Spectralia roburella! I took the entire branch and cut it up to bring back for rearing. We continued hiking along the canyon rim and saw the most amazing views—sheer Cretaceous limestone walls towering 300 feet above the narrow canyon bottoms! Farther down the trail we finally started seeing Acmaeodera on O. engelmannii flowers. By then we’d hiked more than a mile and a half down the trail and temps were beginning to soar, so we turned back, picked up the wood we’d cut as we came back by, and finished the long, hot slog back to the truck.

A mirid bug (Oncerometopus sp.) on flower of Viguiera dentata.
View of cave dwelling area.
Top of a Canyon!
Seminole Canyon stretches from one side to the other.
Seminole Canyon walls.

Comstock
As Rich and I were lunching after our last stop, I got a text from Ed Riley about a spot near Comstock where he’d collected what he believed to be Acmaeodera starrae—a species I’ve never encountered. It just so happened that we would be passing by Comstock on our way back east this afternoon, so we stopped to see if we could find it. Bingo—right where and in the flowers he said it would be (an undetermined white composite that I later determined to be Aphanostephus ramosissimus [lazy daisy]). Together we found about 15 specimens, and interestingly about 25% have red rather than yellow elytra markings. [EDIT: I’m not convinced these are A. starrae, but I do not yet know what they are.]

Aphanostephus ramosissimus (lazy daisy).
Aphanostephus ramosissimus (lazy daisy).

Day 10 – Garner State Park, Wild Horse Creek/Highway/Campos Trails
It’s the final day of collecting for the trip, and for our last stop we picked Garner State Park along the Frío River. I was last here back in the mid 90s—nearly 30 years ago, Acmaeodera ornatoides and Polycesta elata being the two species of note that I remember finding. I remember during that first visit that the area reminded me of my beloved Ozark Mountains, especially the White River Hills region in southwestern Missouri—scraggly forests of oak and juniper on steep, rocky slopes over craggy hill and lazy dale. It still does, although the species are a bit different—Juniperus ashei (Ashe juniper) dominates instead of J. virginiana (eastern red-cedar), and a variety of other oaks replace the familiar Ozarkian Quercus stellata and Q. marilandica (post and blackjack oaks, respectively). We hiked a series of trails on the western side of the park, thinking the west-facing slopes would tend to be drier and result in more open, glade-like habitats, and for the most part this was true. Almost immediately after reaching the first glade along Wild Horse Creek Trail, we found A. ornatoides and at least two smaller congeners on flowers of Coreopsis sp. Flowers of Viguiera dentata have been uncharacteristically depauperate of buprestids on this trip, but I picked up a couple of Acmaeodera neglecta/neoneglecta nearby as well. On the Highway Trail a good series of Acmaeodera was found on flowers of an undetermined small white composite, and a few were also found on flowers of Senna roemeriana (two-leaved senna)—though no Agrilus obtusus. The Campos Trail ascended steeply and ruggedly to a nice overlook, where I found one Acmaeodera sp. on the flower of Zephyranthes chlorosolen and then the mother-load—the biggest diversity and abundance of Acmaeodera I’ve ever seen on cactus flowers occurred nearby in a single flowering Opuntia engelmannii. The final specimen of the day’s “Acmaeodera-a-thon” was taken a bit further up the trail on the flower of Echinocereus enneacanthus (strawberry cactus). Fortunately, the trail was all downhill from there (albeit a bit too steep and rocky at times for these no-longer-nimble legs!). We finished off the hike back along the Wild Horse Creek Trail by collecting a branch off a fallen oak that I hope proves fruitful in the rearing box back home and had some lunch. As we were getting ready to leave, I noticed most of the trees in the camping area were Carya illinoensis (pecans)—a great host for buprestids (especially Xenorhipis brendeli), so I picked up several fallen branches from under the trees to complete the wood collecting portion of the trip.

Acmaeodera ornatoides on flower of Coreopsis sp.
Overlook from atop the Campos Trail.
Xeric limestone prairie (glade) habitat.
Echinocereus enneacanthus (strawberry cactus).
Echinocereus enneacanthus (strawberry cactus).

Garner State Park, Brazos River (epilogue)
We visited the nearby Frio River for one last look at the park, took a shower, and settled in for the 15-hour trek back to St. Louis.

Brazos River at Garner Stare Park, Texas.

Postscript!

Somewhere near Rising Star, Texas.

©️ Ted C. MacRae 2021

Do you think I’m tasty?

As I hiked the upper stretch of the Shut-Ins Trail at Sam A. Baker State Park in southeastern Missouri, I encountered this 2-inch long millipede slowly making its way across the rocks.  Many millipedes, of course, produce hydrogen cyanide (HCN) as their primary method of defense against predation, and the bright yellow markings of this individual were an obvious sign that this particular species is no exception.  The wrinkled dorsal surface and black coloration with yellow wedge-shaped posterolateral markings identify it as a species of Pleuroloma (BugGuide), and of the four species known from North America (Shelley 1980) only the widespread Pleuroloma flavipes (literally meaning “yellow legs”) occurs as far west as Missouri (Shelley et al. 2004).  A similar pattern of coloration is seen in a number of related genera, e.g. Apheloria, Boraria, and Cherokia—all belonging to the order Polydesmida, presumably functioning across the group as an aposematic (warning) signal to predators that they should be left alone.  Another feature shared by the members of this group is the lateral expansion of the dorsal segments into “paranota,” giving the species a much more flattened appearance than other millipedes with the more typical cylindrical shape.  While all millipedes exhibit diplosegmentation (embryonic fusion of paired body somites and associated legs, spiracles, and ventral nerve cord ganglia), members of the Polydesmida have taken this condition to its culmination with no evidence of external sutures (Myriapoda.org).

The bright coloration of this species was an interesting contrast to the cryptic invisibility of the copperhead snake I had seen just a few moments earlier during the hike—opposite strategies with identical goals.  Defense compounds are, of course, widely employed by many plants and animals; however, only millipedes and a few insects have developed the ability to utilize HCN, a highly toxic compound that halts cellular respiration in most animals through inhibition of the mitochondrial enzyme cytochrome c oxidase.  Evidence suggests that Pleuronota flavipes and other millipedes can tolerate HCN because they possess a resistant terminal oxidase that makes their mitochondria insensitive to the effects of HCN (Hall et al. 1971).

Perhaps some of you will be interested in this recent checklist of the millipedes of North and Central America (Hoffman 1999).

Update 6/13/11: My ID as Pleuroloma flavipes must be considered tentative, as Rowland Shelley has sent me an email with the following comment:

It could be Pleuroloma flavipes Rafinesque, 1820, or it could be Apheloria virginiensis reducta, I can’t really tell from the photos.

 

REFERENCES:

Hall, F. R., R. M. Hollingworth and D. L. Shankland. 1971. Cyanide tolerance in millipedes: The biochemical basis. Comparative Biochemistry 34:723–737.

Hoffman, R. L.  1999.  Checklist of the millipedes of North and Middle America. Virginia Museum of Natural History Special Publication No. 8, 584 pp.

Shelley, R. M. 1980. Revision of the milliped genus Pleuroloma (Polydesmida: Xystodesmidae). Canadian Journal of Zoology 58:129–168.

Shelley, R. M., C. T. McAllister, and S. B. Smith. 2004. Discovery of the milliped Pleuroloma flavipes in Texas, and other records from west of the Mississippi River (Polydesmida: Xystodesmidae). Entomological News 114 (2003):2–6.

Copyright © Ted C. MacRae 2011

Answers to ID Challenge #5 – Artrópodes em casca de árvore morta

Dead tree in Campinas, Brazil

After checking into my hotel in Campinas, Brazil I couldn’t wait to start exploring the grounds to see what insect life I might be able to find.  Almost immediately, I encountered this dead tree in back of the hotel.  To a beetle collector, a dead tree is an irresistible draw – especially one that is still standing and with loosely hanging bark, as in this one.  I approached the tree, gave it a look up and down the trunk to see if any beetles or other insects might be found on the outer surface of the bark, and when none were seen began carefully peeling sections of the bark away from the trunk.  Out from beneath the first section darted a small, black lizard – it reminded me in general form of our North American fence lizards (genus Sceloporus), but honestly it darted so fast up the trunk that I didn’t get a good look at it (much less even the chance to attempt a photograph).  Peeling the bark further away from the wood revealed a goodly number of what I took to be beetle larvae, although they were unlike anything I’d ever seen before.  They were fairly good-sized – about 25mm in length, and although there are a number of beetle families whose larvae may be encountered under the bark of dead trees, there aren’t many with larvae of this size.

Coleopteran larva (Tenebrionidae?) under bark of dead tree.

Despite their odd appearance, their basic gestalt suggested to me that they might be something in the family Tenebrionidae (darkling beetles).  Sadly, the state of beetle larval taxonomy is far from complete, especially in the tropics, and given the extraordinary diversity of the order as a whole I knew it could be difficult to impossible to identify them.  This task was further complicated by the fact that I did not collect any voucher specimens.¹

¹ Insect collecting permits are required in Brazil and are exceedingly difficult to obtain.  Although enforcement is lax, a few unlucky foreigners have been caught and suffered tremendous inconvenience at the hands of notoriously unsympathetic authorities.  This being a business trip, I had no desire to tempt fate for the sake of a few larvae in a group I don’t even study.

Despite a millipede-like appearance, six legs and loose cluster of ocelli indicate its true identity.

After consulting all of the print and online resources at my disposal and failing to find a convincing match at even the family level, I began to second guess not only whether these were tenebrionids, but larvae or even beetles.  I’m not aware of any tenebrionids with larviform adult females, but such are common in the Lampyroidea.  That didn’t seem to fit, however, as the latter tend to be much more flattened and armored in appearance, and the round head is really unlike the elongate and narrow head so often seen in that group.  The actually began to wonder if it was even a beetle – most xylophagous beetle larvae are light-colored and rarely so heavily sclerotized, and the antennae are unlike the typical 3-segmented antennae seen with most xylophagous beetle larvae.  In fact, the antennae and the shape of the head actually reminded me of a millipede, but the obvious presence of six legs (and no more) made this untenable (even though 1st instar millipedes are hexapod, the large size of these individuals precludes them from being 1st instar anything).  Eventually, I could only conclude that they were coleopteran – possibly a larviform adult, but more likely larval.  As a last resort I sent photos to Antonio Santos-Silva, a coleopterist at the University of São Paulo.  Although he specializes in Cerambycidae, I reasoned this might be a fairly common species since I had found good numbers on a single tree in an urban area near São Paulo, and as such it might be something he would recognize.  Antonio quickly replied saying that he agreed it was the larva of a species of Tenebrionidae, with an appearance similar to the larvae of Goniodera ampliata (a member of the Lagriinae, formerly considered a separate family).  I’ve not been able to find photos of the larva of Goniadera or related genera, but these do bear a striking (if more glabrous) resemblance to these presumed tenebrionid larvae from Australia.  Until a more convincing opinion is forthcoming, Tenebrionidae seems to be the consensus.

Polyxenid millipedes and two types of Collembola (several Poduromorpha and one Entomobryomorpha)

Three tiny adult coleopterans (family?) surround a large larval coleopteran

Although nobody zeroed in on Tenebrionidae for this challenge (#5 in the ID Challenge series), I must say that I enjoyed the diversity of opinion about what it might represent.  Moreover, congratulations to those who ‘took nothing for granted’ and noted the presence of several other organisms in the photo – this is where the big points were to be earned, and several participants successfully ID’d what I take to be a number of poduromorph collembolans, a single entomobryomorph collembolan, a central cluster of polyxenid millipedes, and several indistinct but clearly coleopteran adults (see super crops above).  David Hubble got the most correct answers to earn 15 points and the win in this inaugural post of BitB Challenge Season #2, while Dave and Troy Bartlett earned 13 and 10 points, respectively, to complete the podium.  Seven other participants got in on the fun and earned some points – I hope you’ll join the fun next time, too!

Copyright © Ted C. MacRae 2011

Millipede assassin bug

Ectrichodia crux

I continue the hemipteran theme begun in the last post with this photograph I took in South Africa below the Waterberg Range in Northern (now Limpopo) Province. I recognized them as members of the family Reduviidae (assassin bugs), and since to my knowledge species in this family are exclusively predaceous (except for the so-called “kissing bugs” of the mostly Neotropical subfamily Triatominae, large distinctive bugs that feed exclusively on vertebrate blood), I found what I took to be a case of scavenging on a dead millipede to be rather curious.  It had rained the previous evening, resulting in a burst of millipede (and insect) activity that night, and this scene was rather commonly encountered the following morning. Of course, appearances can be deceiving, and it turns out that I actually was witnessing predation – and a most unusual case at that.  The individuals in this photo represent Ectrichodia crux (millipede assassin bug), a common species in many parts of southern Africa.  Although nearly 500 species of assassin bugs are known from the region (Reavell 2000), E. crux is easily recognizable due to its large size (adults measure up to 22 mm in length), stout form, and coloration – shiny black, with a distinctive black cross incised on its dull yellow thorax and with yellow abdominal margins (Picker et al. 2002). The nymphs as well are distinctive – bright red with black wing pads. Clearly, these insects are advertising something.

Ectrichodia crux belongs to the subfamily Ectrichodiinae, noted for their aposematic coloration – often red or yellow and black or metallic blue, and as specialist predators of Diplopoda (Heteropteran Systematics Lab @ UCR).  Species in this subfamily are most commonly found in leaf litter, hiding during the day under stones or amongst debris and leaving their shelters at night in search of millipedes (Scholtz and Holm 1985). They are ambush predators that slowly approach their prey before quickly grabbing the millipede and piercing the body with their proboscis, or “beak.”  Saliva containing paralytic toxins and cytolytic enzymes is injected into the body of the millipede to subdue the prey and initiate digestion of the body contents, which are then imbibed by the gregariously feeding assassin bugs.

Millipedes employ powerful chemical defenses – primarily benzoquinones and sometimes hydrogen cyanide gas as well, which are discharged from specialized glands along the millipede’s body – to protect themselves from predation.  Thus, specialized predation of millipedes is a niche that has been exploited by relatively few predators, and little is known about the mechanisms used for circumventing these defenses. The recently reported millipede specialist, Deltochilum valgum (order Coleoptera, family Scarabaeidae), has been observed killing its prey by violently decapitating and disarticulating it before feeding on the body contents (Larsen et al. 2009, summary here); however, the exact manner by which the beetle avoids or withstands the millipede’s chemical discharges remains unknown.  For ambush predators such as Ectrichodia crux and other ectrichodiines, a strategy similar to that described for another millipede specialist predator, larvae of the phengodid beetle, Phengodes laticollis (order Coleoptera, family Phengodidae), might be employed. This species subdues its millipede prey by piercing thinner regions of the millipede’s integument (e.g., intersegmental membranes on the ventral surface) with its hollow sickle-shaped mandibles and apparently injecting gastric fluids that abruptly paralyze the millipede, thereby preventing it from discharging its gland contents (Eisner et al. 1998).  These undischarged benzoquinones remain confined to the glands and are prevented from diffusing into the body cavity by the glands’ impervious cuticular lining, thus allowing the phengodid larva to safely imbibe the liquified systemic contents of the immobilized millipede.

REFERENCES:

Eisner, T., M. Eisner, A. B. Attygalle, M. Deyrup and J. Meinwald. 1998. Rendering the inedible edible: Circumvention of a millipede’s chemical defense by a predaceous beetle larva (Phengodidae).  Proceedings of the National Academy of Sciences USA 95(3):1108–1113.

Larsen, T. H., A. Lopera, A. Forsyth and F. Génier. 2009. From coprophagy to predation: a dung beetle that kills millipedes. Biology Letters DOI:10.1098/rsbl.2008.0654.

Picker, M., C. Griffiths and A. Weaving. 2002. Field Guide to Insects of South Africa. Struik Publishers, Cape Town, 444 pp.

Reavell, P. E. 2000. The assassinbugs (Hemiptera: Reduviidae) of South Africa. http://oldwww.ru.ac.za/academic/departments/zooento/Martin/reduviidae.html#ectrichodiinae.

Scholtz, C. H. and E. Holm (eds.). 1985. Insects of Southern Africa. Butterworths, Durbin, South Africa, 502 pp.

Copyright © Ted C. MacRae 2009

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Done with dung, meat please!

ResearchBlogging.orgNo feces for this species.” “Carnivorous dung beetle shuns dung and decapitates millipede.” “Little dung beetle is big chopper.” “Dung beetle mistakes millipede for dung.” These were some of the clever headlines that I had to compete with in coming up with my own opener for a remarkable beetle that titillated the science blogosphere last week. At the risk of being redundant, I’d like to revisit that beetle and offer a few (hopefully novel) thoughts of my own. I can say that I have a unique and special treat for those willing to read further.

First the background. Deltochilum valgum is a so-called “dung beetle” in the family Scarabaeidae that lives in the lowland rain forests of Peru. As suggested by its common name, it belongs to a group of beetles that are well known for their dung feeding habits. Over 5,000 species of dung beetles are known throughout the world, all of which carve out balls of dung and bury them as provisions for larval development – or so it was thought.  As reported by Trond Larsen of Princeton University and colleagues in Biology Letters, D. valgum has apparently abandoned its ancestral dung ball-rolling behavior in favor of a predatory lifestyle. Its prey – millipedes! Moreover, the species exhibits several distinct morphological traits that appear to have evolved as a direct result of their predatory behavior. Adult beetles were repeatedly observed killing and eating millipedes, and their disdain for dung was rather conclusively demonstrated by an exhaustive, year-long trapping program in which pit-traps were baited with a variety of bait types known to attract dung beetles (e.g., various kinds of dung, carrion, fungus and fruit) – and millipedes.  In all, over 100,000 dung beetles representing 132 species were trapped (what a nice collection!), 35 of which were found to scavenge on dead millipedes, but only five of these dared tackle live millipedes.  Of these, only D. valgum ignored all other foods – it only came to traps baited with live millipedes.

Larsen et al. determined that adults of D. valgum are opportunistic hunters and were much more likely to attack injured millipedes than healthy ones, even those weighing 14 times as much as the beetle.  Ball rolling behavior was never observed by D. valgum.  Most dung beetles have wide, shovel-shaped heads used to scoop and mold dung balls, but D. valgum has a much narrower head with sharp “teeth” on its clypeus (Fig. 1A vs. 1B).  The teeth apparently aid in killing the millipede by piercing the ventral surface behind the head and prying upwards (decapitating it), and the narrow, elongate head facilitates insertion into the millipede body for feeding.  Further, the hind tibia are elongate and curved, which are used to “grip” millipedes by holding them up against the dorsally reflexed pygidium (Fig. 1C vs. 1D).  This allows the beetle to drag its coiled up victim with one hind leg while walking forward on the other five (Fig. 1E).  Once killed, the beetles proceeded to break their prey into pieces and consume their meaty innards, leaving the disarticulated millipede exoskeletons licked clean (Fig. 1F).  One of these “attack” episodes was filmed (using infrared lighting so as not to affect their nocturnal behavior) and can be seen in this BBC News video.

Deltochilum valgum

Figure 1. (a) Dorsal view of D. valgum head. Sharp clypeal teeth and angled clypeus act as a lever to disarticulate millipede. Narrow, elongate head permits feeding inside millipede; (b) dorsal view of Deltochilum peruanum head, lacking characters described in (a), head used to mould dung balls; (c) lateral view of D. valgum pygidium and hind tibia. Dorsally reflexed pygidial lip is used to support millipede during transport. Elongate, strongly curved hind tibia is used to grip millipede. (d ) Lateral view of D. peruanum pygidium and hind tibia, lacking characters described in (c), hind tibia used for rolling dung balls. (e, f ). Predation strategy by D. valgum. (e) Dragging live, coiled millipede with one hind leg, walking forwards; ( f ) feeding on killed millipede with head inside
segments; disarticulated empty millipede pieces nearby.
Credit: Larsen et al. (2009).

Much has been made about this remarkable shift from coprophagy to predation, which Larsen et al. speculate was driven by competition for limited resources with the many other dung beetle species that occur in the Peruvian rainforests. In fact, adult dung beetles are known to feed on a variety of resources besides dung, as exemplified by the range of baits used in their survey. Thus, my first thought after reading the coverage was actually a question: “Has this species abandoned dung provisioning completely as a reproductive strategy?” Everything I had read focused exclusively (quite understandably) on the bizarre feeding habits of the adults, but there was no mention of what the species’ larval provisioning strategies were. Wanting more information about this, I contacted Trond Larsen, who graciously sent me a PDF of the paper. Unfortunately (though not a criticism of the paper), no further insight about this was found in the paper either. Indeed, in all of the observations recorded by Larsen et al., millipedes killed by D. valgum were consumed entirely by the adults, and no mention was made of how or whether millipedes were utilized for larval provisioning. I wondered if D. valgum had truly abandoned dung provisioning for larval development (a remarkable adaptive switch), or if in fact the species might still utilize the strategy for reproduction (perhaps having specialized on a dung type not included in their survey), while also exploiting millipede predation as adults for a nutritional advantage. I asked Trond about this, to which he replied with this juicy tidbit (I told you I had a special treat!):

Yes, I would very much like to know what the reproductive/nesting behavior of D. valgum is. My best guess is that they also use millipedes as a larval food source, but as you say, we haven’t observed that behavior yet. I have observed other generalist dung beetle species rolling balls out of dead millipedes, presumably to bury for the larvae, so I certainly think it would be an adequate food source. Many dung beetle species use carrion for their larvae.

I am quite confident that D. valgum does not use any kind of dung. I have sampled these dung beetle communities very thoroughly, with many dung types and other bait types, and also with passive flight intercept traps that catch all beetles. Every dung beetle species that feeds on dung is at least sometimes attracted to human dung (this is not the case in African savannahs though, but is in neotropical forests – that is a whole different story). There are still a small handful of species we catch in flight intercept traps that we don’t know what they eat, although some of these mysteries have recently been solved – many of them live in leaf-cutter ant nests for example.

While predation of millipedes by a dung beetle is itself a fascinating observation, demonstrating the abandonment of dung provisioning in favor of captured prey for larval development would be a truly remarkable example of an ecological transition to exploit a dramatically atypical niche. I hope Trond (or anybody for that matter) actually succeeds in observing millipede/prey utilization for larval provisioning by this species.

Many thanks to Trond Larsen for his delightful correspondence.

SOURCE:
Larsen, T. H., A. Lopera, A. Forsyth and F. Génier. 2009. From coprophagy to predation: a dung beetle that kills millipedes. Biology Letters DOI: 10.1098/rsbl.2008.0654.

Copyright © Ted C. MacRae 2009

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