2015 Texas Collecting Trip iReport—Fall Tiger Beetles

This is the fourth in a series of “Collecting Trip iReports”—so named because I’ve illustrated them exclusively with iPhone photographs. As I’ve mentioned in previous articles in this series (2013 Oklahoma2013 Great Basin, and 2014 Great Plains), I tend to favor my iPhone camera for general photography—i.e., habitats, landscapes, miscellaneous subjects, etc.—during collecting trips and save my full-sized dSLR camera only for those subjects that I want high-quality macro photographs of. iPhones are not only small, handy, and quick but also capable (within reason) of quite good photographs (see this post for tips on making the most of the iPhone camera’s capabilities). This keeps the amount of time that I need to spend taking photos at a minimum, thus allowing more time for the trip’s intended purpose—collecting! Those photos form the basis of this overall trip synopsis, while photos taken with the ‘real’ camera will be featured in future posts on individual subjects.

Last year during late September and early October I travelled to eastern and central Texas. This trip was all about fall tiger beetles, in particular certain subspecies of the Festive Tiger Beetle (Cicindela scutellaris) and Big Sand Tiger Beetle (Cicindela formosa) found in that area that I had not yet seen. I enjoy all collecting trips, but fall tiger beetle trips are among the most enjoyable of all—cooler temperature, a changing landscape, and charismatic subjects that are both fun and challenging to find and photograph. This trip was no different, with spectacular weather during the entire week and, for the most part, great success in finding the species/subspecies that I was after. At this point I’d like to acknowledge the help of several people—David Hermann (Ft. Worth, Texas), David Brzoska (Naples, Florida), and Steve Spomer (Lincoln, Nebraska), who generously provided information on species and localities. My success at finding these beetles was due in large part to the information they provided.


Day 1 – Cobb Hollow

My car

Little question about what I am doing out here.

After driving 700 miles from my home near St. Louis, I arrived at the first stop of trip—Cobb Hollow in north-central Texas. This small creek lined with deep, dry sand is close to Forestburg (Montegue County)—the type locality of Cicindela scutellaris flavoviridis, a beautiful, all-green subspecies with the elytra suffused golden-yellow.  The habitat looked very promising from the start, and it wasn’t long before I found the first tiger beetle of the trip—a gorgeous, red nominate Big Sand Tiger Beetle (Cicindela formosa formosa). Not long after that I found the first Cicindela scutellaris flavoviridis, and over the next few hours I would find a total of nine individuals. Despite the extensive habitat along the creek the beetles were quite localized, occurring primarily in two dry sand areas within a mile west of the bridge. This spot is actually near the northern limit of the subspecies’ distribution, and several of the individuals showed varying influence from nominate scutellaris with the elytra tending to be more red than yellow-green. There was a diversity of other tiger beetles here as well—C. formosa formosa was the only one that was common, but I did find also a few individuals each of Tetracha carolina, Cicindelidia punctulata, Cicindela splendida, and C. repanda. A very cool place.

Cobb Hollow from bridge

View of Cobb Hollow east from the bridge

Sand bar along creek

Dry sand deposits line the creek.

Robber fly with bumble bee prey

I watched this robber fly snag a bumble bee in mid-flight.

Ted MacRae at Cobb Hollow

Looking down onto the creek from the bridge.


Day 2 – Stalking the Limestone Tiger Beetle

Today was all about looking for the Limestone Tiger Beetle, Cicindelidia politula. I have collected this species previously at several sites in Erath and Somervell Counties, Texas (west of Ft. Worth) and featured photographs from that trip. However, since I would be passing through the area on my way south I decided to spend a day looking for it again and, hopefully, collecting a few more specimens. Cicindelidia politula is related to the much more common and widespread Punctured Tiger Beetle, C. punctulata, but is shiny blue-black with the elytral markings absent or limited to the apices and the abdomen red. I visited several localities—two new ones for me in Erath County and another I had visited previously in Somervell County, with habitats that ranged from rocky clay to white limestone exposures along roadsides and even limestone gravel.

I found a fair number of individuals at the first site (1.7 mi SW Bluff Dale, Jct US-377 & FM-1188), which had a finely ground limestone substrate. Most of the individuals were flushed from the base of clumps of bunch grass and captured when they landed in more exposed situations.

Limestone habitat for Cicindelidia politula

Cicindelidia politula habitat—1.7 mi SW of Bluff Dale.

The beetle had also been reported along the roadsides at the second location (0.4 mi E Jct FM-2481 on CR-539), but the only individual I saw here was on a very coarse crushed limestone 2-track leading off of the main road.

Limestone habitat for Cicindelidia politula

Cicindelidia politula habitat—0.4 mi E Jct FM-2481 on CR-539.

The species was most numerous at the third site in Somervell County (3.4 mi SE Jct US-67 on CR-2013). I collected ten individuals and saw probably that many more on white limestone exposures along the roadside and along a dirt road cut along the base of the hill to the NE side of the highway. Most of the beetles in the latter area were seen along the scraped dirt road (at left in 2nd photo below), although presumably the beetles also utilized the undisturbed, surrounding habitat.

Limestone habitat for Cicindelidia politula

Cicindelidia politula habitat on white, limestone exposures along the roadside.

Limestone habitat for Cicindelidia politula

Cicindelidia politula habitat on white limestone hillside and scraped dirt road.

Catching the beetles at this last locality was challenging—the adults are fast and flighty, and the rough, rocky habitat made it difficult to clamp the net over the beetle and pounce on top of the rim before they were able to find a gap and escape. With practice I found my catch efficiency increased a little bit if I slowly approached the beetle and then made an assertive swing with the net right when the beetle began to fly—the trick is learning how to tell when they are ready to fly (and “assertive” is the key word!). Tiger Beetle Stalker; however, does not quit!

Tiger beetle stalker!

Tiger Beetle Stalker!


Day 3 (Part 1) – Pedernales Fall State Park

This was another locality where Cicindela scutellaris flavoviridis had been recorded. I came here to find this subspecies even though I had seen it two days previously at Cobb Hollow, because that latter population showed some slight intergradation of characters from nominate C. scutellaris and I wanted to get field photographs of a “pure” population. I was pretty excited when I saw extensive dry sand habitat lining the upper bank area along the Perdenales River; however, I found no tiger beetles of any kind after extensive searching through that habitat. I did note the area seemed dry and reasoned that perhaps timely rains had not yet triggered emergence of C. scutellaris, C. formosa, and other sand-loving fall tiger beetles. I did find a small area of wet sand right along the water’s edge where three species of Cicindelidia could be seen: C. ocellata rectilatera, C. trifasciata ascendens, and C. punctulata. I’ve photographed all of these species before, so I didn’t try to spend any time doing so here. However, combined with the species seen the previous two days, this made a total of ten species seen on the trip so far. Although I didn’t find the beetle I was looking for, I marveled at the beauty of the area, especially the Pedernales River with its hard, conglomerate bedrock and mini shut-ins and spent quite a bit of time here taking photographs.

Perdenales River

The Perdenales River is the centerpiece of the state park.

Schistocerca americana or nitens

Schistocerca americana or S. nitens (ID courtesy of Matt Brust).

Perdenales River

Shut-ins are extensive along the Perdenales River.

Poecilognathus sp.

Bee flies (family Bombyliidae), prob. Poecilognathus sp. (ID courtesy Rob Velten).


Day 3 (Part 2) – Lick Creek Park

Another of the Festive Tiger Beetle subspecies that I wanted to look for was Cicindela scutellaris rugata. I had several localities from which this solid blue-green subspecies has been recorded, and this site was the nearest of those that I planned to visit. The drive from Pedernales State Park was longer than I anticipated, so I didn’t get to this spot until close to 6 p.m. At first I worried that I wouldn’t have enough time to even find suitable habitat, but that was no problem as I quickly found the Post Oak Trail and its perfect open, post oak woodland with deep sand substrate. By all accounts the beetles should have been all over the trail but they weren’t. As with the previous site, the area was quite dry as evidenced by the wilted plants along the trail side, and I also note that the previous record from here was on Oct. 23rd—more than three weeks later. Despite the fact that I didn’t find any tiger beetles, I did see a young timber rattle snake (Crotalus horridus) crossing the trail late in the hike—I took a quick shot with the iPhone (see below) and then broke out the big camera and was able fire off a few shots before it left the trail and headed for cover. (Several people walking the trail came upon us, and they were all—happily—more than willing to oblige my requests to stay away until I was finished.)

Sand woodlant habitat for Cicindela scutellaris rugosa

Post oak woodland with dry sand substrate seems to be perfect for Cicindela scutellaris rugata.

Wilted American beautyberry (Callicarpa americana)

Wilted American beautyberry (Callicarpa americana).

Timber rattlesnake (Crotolus horridus)

A youngish (prob. ~32″ in length) timber rattlesnake (Crotolus horridus) was a treat to see.


Day 4 – East Texas cemeteries

Cemeteries are often great places to look for tiger beetles because they tend to be located on parcels of land with low agricultural value that were donated by landowners to local churches. Older cemeteries especially tend not to be highly maintained and, thus, offer excellent habitat for tiger beetles. My goals for this day were Cicindela scutellaris rugata and the gorgeous Cicindela formosa pigmentosignata. I had records of both from a couple of cemeteries in eastern Texas (Sand Flat Pioneer Cemetery in Henderson and Morris Chapel Cemetery in Van Zandt Counties) and found good numbers of both along sandy 2-tracks and sparsely to moderately vegetated sand exposures in and around the cemetery grounds. I don’t have any iPhone photographs to share of either of these species, but I did spent a lot of time with the big camera and got a number of photos of each that I am quite pleased with—I’ll share those in future posts. The cemeteries themselves were haunting and poignant, with some headstones dating back to the late 1800s.

Sandy 2-track habitat for Cicindela scutellaris rugata & C. formosa pigmentosignata

Sandy 2-track habitat for Cicindela scutellaris rugata & C. formosa pigmentosignata at Sand Flat Pioneer Cemetery, Henderson County, Texas.

 

Ant mound

Pogonomyrmex sp. poss. barbatus tend their nest entrance (ID courtesy of Ben Coulter).

Sand Flat Pioneer Cemetery

Oldest section of Sand Flat Pioneer Cemetery.

Died Nov 10, 1874

Fallen, but not forgotten—yet (died Nov 10, 1874).

Oldest headstones (late 1800s)

Oldest headstones (late 1800s) at rest under the shade of huge, red-cedar trees.

Oldest person (106 yrs old)

The oldest person died at 106 years of age (born in 1804).

At Morris Chapel Cemetery I found C. formosa pigmentosignata and C. scutellaris rugata on sparsely vegetated deep dry sand 2-track north of the cemetery. I did also manage to get field photos of the former before it got too hot and they became too active. There were also a few of the latter in the open sandy ground just outside the northwestern edge of the cemetery. As with Sand Flat Pioneer Cemetery, I spent a bit of time in the cemetery proper to look at the headstones—the oldest headstone also being the most poignant; a one and a half-year old boy who died in 1881.

Sandy 2-track habitat for Cicindela scutellaris rugata & C. formosa pigmentosignata

Sandy 2-track habitat near Morris Chapel Cemetery.

Morris Chapel Cemetery

A large, spreading post oak shades pioneers at rest.

Died 1881 (age 1½ yrs)

A poignant headstone (died 1881 at 1½ years of age).

After finishing up at Morris Chapel Cemetery I returned to Sand Flat Cemetery to see if I could get more field photographs before the beetles bedded down for the night. The sun was still up when I arrived a little before 6 p.m., but the shadows were long and no beetles were seen. Not one to waste an opportunity, I broke out the big camera anyway and started photographing a large species of bee fly (family Bombyliidae) that was perching on the ground and on the tips of plains snakecotton (Froelichia floridana).

Undet. bee fly

Bee fly (family Bombyliidae), poss. Poecilanthrax lucifer? (ID courtesy Alex Harman).


Day 5 (Part 1) – Cowtown Bowman Archery Club

With both specimens and good field photos of Cicindela scutellaris rugata and C. formosa pigmentosignata in hand, I returned my attention to C. scutellaris flavoviridis. Again, I did already have specimens in hand from Cobb Hollow, but most of them showed some degree of intergradation with nominate C. scutellaris and I was hoping to see some “pure” individuals. Failing to find it at the more southerly locations (Pedernales State Park and Lick Creek Park), I had one more location in Tarrant County where the subspecies had been recorded—a sand borrow pit near the entrance of Cowtown Bowman Archery Club. Once again I searched the area thoroughly for a couple of hours during mid-morning but did not see the subspecies or any other tiger beetles. Conditions were overcast and cool (72°F), but I do not think this explains the absence of adults. Rather, I think I was on the early side of the season and they just hadn’t started emerging at this site.

While I was at the site I found several tiger beetle larval burrows in a moderately vegetated area near the deeper sand deposits that were occupied by Tetracha carolina, so I used the “stab” or “ambush” method to collect several 3rd instars for an attempt at rearing. For those of you who are not familiar with this technique, a knife is set at a 45° angle with the tip in the soil about 1″ from the edge of the burrow. Then you wait, sometimes for quite a while, until the larva reappears at the top of the burrow and STAB the knife assertively into the soil to block the larva from retreating. The larvae are extremely wary with excellent vision and will usually drop back down immediately when they see you, so you have to be ready and act quickly. Once the retreat is blocked, a simple twist of the knife to expose the larva is all that is needed. I prepared larval habitats by placing native soil with as intact a top layer as possible in plastic critter carriers, made a starter hole for each larva with a pencil, dropped each larva into one of the holes, and then pushed the soil to seal the burrow entrance. This prevents the larvae from crawling right back out of the starter burrow, which can result in them encountering and fighting each other. The larvae will eventually reopen the burrow entrance, but after being sealed inside for a while they usually accept the burrow and further modify it to suit their needs.

 

Sandy grassland habitat for Tetracha prob. carolina

Sandy grassland habitat for Tetracha carolina.

Larval burrows (lower left) can be recognized by their clean, almost perfectly round, beveled edge. The presence of fresh soil diggings cast to one side (upper right) indicates the burrow is occupied by an active larva.

Tetracha prob. carolina larval burrow

Tetracha carolina larval burrow with cast soil diggings.

Using the “stab” or “ambush” method to collect larvae. One must have patience to successfully use this method.

"Stab 'n; grab" method to collect tiger beetle larvae (Tetracha prob. carolina)

Using the “stab” or “ambush” method to collect tiger beetle larvae.


Day 5 (Part 2) – Cobb Hollow (epilogue)

Although I had found Cicindela scutellaris flavoviridis at this site on the first day of the trip, I had not taken any field photographs in hopes of finding a more “pure” population at one of the more southerly locations. That did not happen, so I returned to Cobb Hollow on this last day in the field to get field photographs from the population there. Temperatures were a bit cooler (mid-70s) and cloud cover was variable, actually sprinkling when I arrived mid-afternoon but eventually clearing. This seemed to have no detrimental effect on adult presence, and it may have actually helped as I was able to photograph the very first individual that I found to my heart’s content. I collected that individual and the next three that I saw by hand and found two more over the next hour—all on the same deep, dry sand bars west of the bridge where I had seen them previously. Curiously, Cicindela formosa was strangely absent from these same areas where they had been so numerous a few days earlier.

Habitat for Cicindela formosa formosa and C. scutellaris flavoviridis

Deep, dry sand deposit where most of C. scutellaris flavoviridis were seen.

On the east side of the bridge I collected two more Tetracha carolina in the same moderately vegetated sandy clay spot as last time, then went on to the furthest dry sand bar where I found and photographed (but did not collect) a single C. formosa (only one shot before it took off). I also found a female green lynx spider (Peucetia viridans) sitting on her egg mass and got some nice macro photos as well as this iPhone shot (talk about a face only a mother could love!).

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Female green lynx spider (Peucetia viridans) atop her egg mass.


I hope you’ve enjoyed this collecting trip iReport. Stay tuned for true macro photographs of the tiger beetles and other insects/arthropods that I photographed on this trip in more subject-specific posts. You are also welcome to leave feedback in the comments below.

Ted MacRae w/ field collecting equipment & camera

© Ted C. MacRae 2016

Party on a pin oak

In September 2012 while collecting in western Oklahoma (Weatherford) I came across this interesting scene. It had been exceedingly dry in the area, and because of this few insects were out and about in the small city park that I stopped by to check for the presence of tiger beetles. I had nearly completed my circuit of the park when I came upon a moderate-sized pin oak (Quercus palustris) tree and noticed something on the lower trunk:

Six insect species representing five families in four orders share a sap flow.

Six insect species representing five families in four orders share a sap flow on the trunk of a pin oak.

No less than six insect species representing four orders were seen all huddled together at a darkly stained sap flow. This could be the result of slime flux, a bacterial disease that usually affects deciduous hardwoods that are under stress and results in darkly stained weeps on the trunk that are known to be attractive to a variety of insects. At the center sat a green June beetle (Cotinis nitida) and three bumble flower beetles (Euphoria inda)—all in the family Scarabaeidae (subfamily Cetoniinae). Covering the scarab beetles were half a dozen Texas Tawny Emperor (Asterocampa clyton texana) butterflies (family Nymphalidae, or Brushfooted Butterflies), and milling around the perimeter was a velvet ant (Dasymutilla creusa, I believe) in the family Mutillidae, an apparent flesh fly (family Sarcophagidae), and a true ant (family Formicidae). I guess this would be the equivalent to a watering hole in Africa with a lion, a hyena, a baboon, three vervet monkeys and six zebras all crouched shoulder-to-shoulder at its edge.

Euphoria sepulchralis feeds on a sap flow higher up on the trunk.

Euphoria sepulchralis feeds on a sap flow higher up on the trunk.

Further up on the trunk, yet another species of scarab beetle, a dark flower scarab (Euphoria sepulchralis) was found feeding on a smaller sap ooze. Unlike the diverse aggregation of insects on the lower ooze, this guy had managed to keep the ooze all to himself.

Cotinus nitidus | Weatherford, Oklahoma

Cotinis nitida | Weatherford, Oklahoma

Green June beetles, especially, are known for their feeding on sap oozes. The beetles are actually attracted to the odors caused by fermentation of the sap rather than the sap itself. It has been reported that the presence of alcohol in fermenting sap can affect the behaviour of insects that feed upon it, causing them to act “stupid and lethargic.” I did not see any such behavior, but I did notice that the insects were not at all skittish and loath to leave the sap.

Copyright © Ted C. MacRae 2013

Red-eyed poop!

I was looking at some of my older files and ran across these photographs taken in early 2011 in Campinas (São Paulo state), Brazil. They’re not my best photos from a compositional and technical perspective, as I was still on the steep part of the learning curve with the Canon MP-E 65mm macro lens. This lens is no doubt powerful and allows amazingly close-up photographs, but it is rather a beast to learn in the field, especially hand-held. I could quibble endlessly about missed focus and suboptimal composition with these shots, and that is probably why they never made it to the front of the line for being posted. Nevertheless, they still depict some interesting natural history by one of nature’s most famous natural history poster children—the treehoppers (order Hemiptera; family Membracidae).

An adult next to a cast nymphal exuvia.

Bolbonota sp. (Hemiptera: Membracidae), upper right | Campinas, São Paulo, Brazil. Note cast exuvia.

The treehoppers shown in these photos were found on a low shrub in a municipal park and are all that I could manage before my clumsy, unpracticed molestations caused the few adults and nymphs present in the aggregation to disperse. The dark coloration of the adult and its globular form, corrugated pronotal surface, and lack of any horns identify the species as a member of the genus Bolbonota in the New World tribe Membracini (another similar genus, Bolbonotoides, occurs as a single species in Mexico). Species identification, however, is much more difficult, as there are at least a dozen species recorded from Brazil and perhaps many more awaiting description. We have a similar though slightly more elongate species here in eastern North America, Tylopelta americana. I don’t know if this is a specific character or not, but I don’t recall seeing any members of this genus with smoldering red eyes—it gives them an almost devilish appearance, especially the blackish adults (see last photo)!

Bolbonota sp. late-instar nymphs clustered together.

Bolbonota and similar genera are often cited by evolutionists as examples of insects that mimic seeds. I can see such a resemblance if I force myself, but honestly I don’t really buy it. To me they seem to bear an uncanny resemblance to the chlamisine leaf beetles which are thought to mimic caterpillar frass. As with the beetles they resemble, frass-mimicry seems to make much more sense than seed-mimicry, especially given their preference for positioning themselves along the stems of the plants on which they feed (when was the last time you saw seeds of a plant randomly distributed along its stems?). Another thought I’ve had is that this is not an example of mimicry at all, but merely an accidental consequence of the heavy, corrugated body form they have adopted, which likely also affords them a reasonable amount of protection from predation. Confounding both of these theories, however, are the radically different appearance and form of the adults versus the nymphs, and indeed even between the different nymphal instars (see early- and late-instar nymphs in photo below). The later instars seem perfectly colored for mimicking unopened leaf buds, but why they would start out dark in early instars before turning mottled/streaked-white as they mature, only to revert back to dark when reaching adulthood, is a mystery to me. If my thoughts are anywhere close to the truth, it would be a remarkable case of different life stages mimicking the products of two different taxonomic kingdoms (plant parts as nymphs, animal poop as adults)!

Bolbonota sp. nymphs tended by Camponotus sp. | Campinas, São Paulo, Brazil.

An ant (presumably Camponotus sp.) tends a first-instar nymph alongside a later instar.

Of course, if either/both of these lines of defense fail then there are the ant associates that often protect treehoppers and other sap-sucking, aggregating insect species in exchange for the sweet, sugary honeydew that such insects exude as a result of their sap-feeding habits. I presume this ant belongs to the genus Camponotus, perhaps C. rufipes or C. crassus which are both commonly encountered treehopper associates in southern Brazil. I have written previously about ant-treehopper mutualism in the stunningly-marked nymphs of another treehopper, Guayaquila xiphias, and its ant-associate C. crassus in Brazil Bugs #15 – Formiga-membracídeos mutualismo (a post that has become one of this blog’s most popular all-time). Maybe this post will never match that one in popularity, but I do find the third photo shown here remarkable in that is shows no less than five elements of this treehopper’s natural history (early-instar nymph, late-instar nymph, cast nymphal exuvia, partial adult, and an ant-associate) within a single frame (shot by a person still on the steep portion of the MP-E 65mm learning curve!).

Copyright © Ted C. MacRae 2013

Fire ant winged reproductives: male and female

While in Austin at the Entomological Society of America meetings, I had the chance to tour The University of Texas at Austin’s Brackenridge Field Laboratory.  Located on 82 acres of land bordering the Colorado River, the station supports studies in biodiversity, ecosystem change and natural history. A major focus of research at the station involves efforts to establish biological control agents for control of imported fire ant (Solenopsis invicta) using entomopathogens and parasitoids (e.g. phorid flies in the genus Pseudacteon). This research relies on maintaining cultures of fire ants to support rearing of the phorid fly. While time was limited and I did not have much opportunity to photograph either the ant or the fly, I did manage to quickly sneak in a shot or two of some winged reproductives that were removed from the teaming formicid mass in a rearing tray and placed on a table top for all to see (and when I say “a shot or two” I mean it. I had the chance only for one shot of the female and two of the male as they crawled crazily about and the tour leader quickly tried to move us on). I’m sure Alex Wild has all stages/forms of this species covered in spades, but the sexually dimorphic winged reproductives were new for me, and perhaps some readers of this blog as well.

Solenopsis invicta winged reproductives: male (top), female (bottom).

Solenopsis invicta winged reproductives: male (top), female (bottom).

Copyright © Ted C. MacRae 2013

The “silky-bellied humpbacked” ant

Last year during my extended work stay in Argentina, I was able to slip away from my duties during the first week of April and spend some time in the city of Corrientes in the northeastern part of the country. The city is one of my favorites in Argentina, but what I love most about it is its convenience as a base camp for exploring some of the habitats in the Grand Chaco ecoregion of northern Argentina. One day I had a chance to visit Chaco National Park about 100 km northwest of the city, site of some of the last remnants of the great quebracho forests that once covered much of northern Argentina. The forest preserved at Chaco NP takes its name from the quebracho colorado chaqueño (Schinopsis balansae) trees that dominate it, standing in defiant contrast to the vast, hot sea of cotton fields and mesquite fence-rows that surrounds it. While hiking a trail through the heart of the forest, I looked down to see a most impressive ant crawling across the forest floor:

Camponotus sericeiventris

Camponotus sericeiventris | Chaco National Park, Argentina

Because of its black color and the striking, silky sheen of the abdomen, I was immediately reminded of the Camponotus mus ants that I had photographed a year earlier further south in Buenos Aires. However, this fellow (er, fella…) was considerably larger than that species, and looking at the photographs later I was also struck by the acute spines at the humeral angles of the pronotum (in C. mus the humeral angles were obtuse) and the flattened legs. All of this combined to make it one of the most handsome ants that I had ever seen! I posted the above photo on my Facebook page asking for ID help, and James Trager quickly responded that the ant represents Camponotus sericeiventris, which translates roughly to “silky-bellied humpbacked” ant. Now there’s a common name I can get behind.

Camponotus sericeiventris

Of course, it turns out that I could have easily determined the species on my own using the characters I had already noted—primarily the acute spines. Googling “camponotus acute spines” retrieves as its first result a paper by Wheeler (1931) that discusses this ant and a newly discovered (at the time) cerambycid beetle, Eplophorus velutinus [now Euderces velutinus] mimicking the ant (Fisher 1931). As soon as I read Wheeler’s first paragraph I knew I had the right species:

Camponotus (Myrmepomis) sericeiventris, owing to its size, wide distribution and dense covering of silver or golden pubescence, is one of the handsomest and most conspicuous ants of the American tropics.

Apparently this ant is a popular choice of models for mimics in a number of insect groups. Lenko (1964) reported another cerambycid beetle, Pertyia sericea, as a mimic of C. sericieventris (the similarity of species epithets being no coincidence), and friend and colleague Henry Hespenheide has not only described a zygopine weevil, Copturus paschalis, from Costa Rica as a mimic of this ant (Hespenheide 1984) but also postulated mimicry by Apilocera cleriformis [now Euderces cleriformis] and three other species of Cerambycidae collected by him in central Panama. Henry further noted mimics in the families Cleridae and Mutillidae and the fact that all of the beetle mimics of this arboreally foraging ant are themselves woodborers or predators of woodborers as larvae.

It is interesting that Fisher (1931), in his description of E. velutinus, made no mention of the mimicry, while Wheeler (1931) in his paper about C. sericeiventris discussed this in great detail. He further noted the diversity of cerambycids here in our North American fauna that mimic ants. These include species in the genera Clytoleptus, Euderces, Cyrtophorus, Tilloclytus and—most strikingly—Cyrtinus pygmaeus, our smallest species of Cerambycidae which occurs on dead wood among small ants such as Lasius americanus, and Michthisoma heterodoxum which resembles small Camponotus pennsylvanicus workers. I’ve not yet encountered M. heterodoxum, which seems restricted to the southeastern Coastal Plain, but I have beaten C. pygmaeus from dead branches and can personally attest to the effectiveness of their mimicry—some slight something about the way they moved made me question my immediate assumption that they were ants and caused me to take a closer look at them before I shook them off the beating sheet. I wonder how many times before that I collected this species without realizing it!

REFERENCE:

Fisher, W. S. 1931. A new ant-like cerambycid beetle from Honduras. Psyche 38:99–101.

Hespenheide, H. A. 1984. New Neotropical species of putative ant-mimicking weevils (Coleoptera: Curculionidae: Zygopinae). The Coleopterists Bulletin 38(4):313–321.

Lenko, K. 1964. Sobre o mimetismo do cerambicideo Pertyia sericea (Perty, 1830) com Camponotus sericeiventris (Guerin, 1830). Papéis Avulsos de Zoologia (São Paulo) 16:89–93.

Wheeler, W. M. 1931. The ant Camponotus (Myrmepomis) sericeiventris Guérin and its mimic. Psyche 38:86–98.

Copyright © Ted C. MacRae 2013

The 2nd-oldest Known Myrmicine Ant

Among the 20 or so insects represented in the Green River Formation (GRF) fossils that I currently have on loan, this rather obvious ant (family Formicidae) is the only one that is firmly assignable to the order Hymenoptera (wasps, bees and ants). This is not surprising, as hymenopterans are not well represented among GRF insect fossils. In fact, of the 300+ insect species that have been described from GRF deposits (Wilson 1978), more than two-thirds belong to just three orders—Diptera (flies), Coleoptera (beetles) and Hemiptera (true bugs). Hymenoptera, on the other hand, comprise only 4% of GRF fossils (Dlussky & Rasnitsyn 2002). I presume these numbers are more a result of taphonomic (fossil formation) bias than a true reflection of insect diversity in western North America during the Middle Eocene (47–52 mya).

cf. Myrmecites rotundiceps | fossil impression from the Green River Formation (45 mya, middle Eocene)

cf. Myrmecites rotundiceps (length = 6.7 mm).

Ants in particular have been poorly represented by GRF deposits. Only four named species were known until Dlussky & Rasnitsyn (2002) reviewed available GRF fossils and increased the number to 18 (15 described as new, one older name placed in synonymy). Diagnoses, line drawings, and keys to all covered subfamilies, genera and species provide one of the best treatments to GRF insect fossils that I’ve come across. According to that work, the fossil in these photos seems comparable to the description and illustration given for Myrmecites rotundiceps, a unique fossil with the general appearance of ants in the subfamily Myrmicinae but differing from all known Eocene and New World fossil ants by its very short, two-segmented waist. The only difference I noted was size—6.7 mm length for my fossil versus 5.5 mm for the holotype (see figure below). Of course, I’m more comfortable identifying extant Coleoptera than extinct Formicidae, so I contacted senior author Gennady M. Dlussky to see if he agreed with my opinion. He graciously sent the following reply:

I agree that specimen on your photo is very similar to Myrmecites rotundiceps. It is larger (holotype is 5.5 mm long), but it may be normal variability. I cannot see another differences.

Myrmecites rotundiceps, holotype (Gennady & Rasnitsyn 2002)

Myrmecites rotundiceps Gennady & Rasnitsyn 2002, holotype (reproduced from Gennady & Rasnitysyn 2002)

If correctly assigned, M. rotundiceps is the second oldest known member of the subfamily Myrmicinae—the oldest being Eocenidris crassa from Middle Eocene Arkansas amber (45 mya). In fact, the only older ant fossil of any kind in North America is Formicium barryi (Carpenter) from Early Eocene deposits in Tennessee (wing only). [Edit: this is actually the only older Paleocene ant fossil—there are some Cretaceous-aged fossils such as Sphecomyrma freyi (thanks James Trager).] Since myrmicine fossils of comparable age are lacking from other parts of the world, this might suggest a North American origin for the subfamily; however, it could also be an artifact of incomplete knowledge of ants from older deposits in other parts of the world. Myrmicine ants make their first Eurasian appearance in Late Eocene Baltic amber deposits (40 mya) and become more numerous in North America during the early Oligocene (Florissant shales of Colorado, 33 mya). (Dlussky & Rasnitsyn (2002) consider the Middle–Late Eocene ant fauna to represent the beginnings of the modern ant fauna, with extant genera becoming numerous and extinct genera waning but still differing by the preponderance of species in the subfamily Dolichoderinae over Formicinae and Myrmicinae.

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USA: Colorado, Rio Blanco Co., Parachute Creek Member.

The photo above shows the entire fossil-bearing rock (also bearing the putative orthopteran posted earlier).

My thanks to Gennady Dlussky and James Trager for offering their opinions on the possible identity of this fossil.

REFERENCES:

Dlussky, G. M. & A. P. Rasnitsyn. 2002. Ants (Hymenoptera: Formicidae) of Formation Green River and some other Middle Eocene deposits of North America. Russian Entomological Journal 11(4):411–436.

Wilson, M. V. H. 1978. Paleogene insect faunas of western North America. Quaestiones Entomologicae 14(1):13–34.

Copyright © Ted C. MacRae 2012

Pseudomyrmex in Corrientes, Argentina

Early April is early autumn in northeastern Argentina, but seasons just south of the Tropic of Capricorn bear little resemblance to the well-defined spring, summer, fall and winter that we are accustomed to in eastern North America. Early fall here is not a riot of color, pungent smells, and sharp shadows cast from an oblique sun, but rather dull greens and browns, muted and dusty after eight months under a searing overhead sun with only the sparsest of rains for the past two. Such conditions are generally not conducive to insect life, and for the most part insects that live in warm, seasonally wet environments adapt by timing their adult activity (the time for reproduction) to the moist seasons—which in this part of Argentina means September through January. Thus, despite warm temperatures and a subtropical environment, early April is not the best time to be looking for insects here.

Pseudomyrmex sp. | Corrientes, Argentina

Nevertheless, not all insect groups respond in this fashion, and one in particular is as ubiquitous and diverse now as at any other time of year—ants! I had to trek into sand and mud along the Rio Paraná to find tiger beetles (a few), and it took some dedicated searching to ferret out a few stands of late-season blooming plants and fresh-cut woodpiles to encounter a small diversity of longhorned beetles. I think I may have even seen a single jewel beetle, a chrysobothrine of some type, as it landed on and then flash flew away from the same woodpile with which I had modest longhorned beetle success. The ants, however, have been everywhere—no tree, shrub, or square meter of ground is without them in astounding diversity of size and form.

At this point it appeared to be eating something it plucked from the bark.

I probably shouldn’t admit this, as I hear rumor there are a few myrmecologists that frequent this blog, but I have a hard time getting excited about ants. I know, their unique social structures and evolutionary history are among the most fascinating in the insect world, and watching their behaviors is a lesson in charisma beyond reproach. Still, however, for me there are just so many of them and their taxonomy so completely foreign to me that every time I try digging further I feel immediately overwhelmed. Coleopteran taxonomy may be an order of magnitude more diverse, but since I only pay attention to about 1.5% of the order, it’s as comfortable to me as an old shoe.

Close...

There is one group of ants that I do find endlessly fascinating—the genus Pseudomyrmex. I don’t know why that should be the case—there are plenty of other ant genera that seem to have the tools and structures that usually grab my attention (e.g., grossly oversized mandibles, sharp spines, heavy duty surface sculpturing, etc.). Pseudomyrmex spp. have none of these morphological gimmicks—just a simple, elongate, wasp-like form. Perhaps it’s their association with branches (like wood-boring beetles) rather than the ground—nope, tiger beetles are decidedly ground dwellers and I dig them (Get it? Heh!). No, it must be their super-sized eyes. Most ants have beady little eyes that make it hard to look into their soul. Pseudomyrmex eyes have charisma—you can see them looking at you (and almost read their thoughts).

closer...

Anyway, among the many ants that I’ve noted wandering the banks of the Rio Paraná here in Corrientes are these smallish, orangish Pseudomyrmex spp. This particular individual was the first one I saw, revealed when I happened to pull away a bark chip from trunk of the palm tree on which it was hiding. It wandered all over the palm trunk for the next 15 minutes or so as I chased after it with my 65mm lens. For such tenaciously crawling subjects I’ve found that simply firing off shot after shot as you track it in the view-finder rather than waiting for it to pause and trying to compose each shot is the best way to get some usable images. It’s simply a numbers game—the more shots you fire off, the better chance you have that at least some will be in-focus, nicely composed, and well-lit. These are the ones I was happiest with from the session. (And, OMG, did I really just give advice on how to photograph ants?)

Closest!

It goes without saying that a more specific ID, if possible, would be greatly appreciated (should any prominent myrmecologists happen across these photos). There are scads of species in this genus right across the river in Paraguay, and presumably the diversity in Argentina is similarly high.

Copyright © Ted C. MacRae 2012

Leafcutter ants on corn

Leafcutter ants attacking corn | western Buenos Aires Prov., Argentina

North American corn farmers certainly have their share of insect pests to worry about. Between corn borer, earworm, armyworm, and rootworm, there isn’t much of the plant that isn’t vulnerable to attack by at least one of these insects. Argentina corn farmers have all this and more—have you ever seen ants attacking corn? I took these photographs yesterday in a corn field in western Buenos Aires Province showing leafcutter ants dining on the developing kernels of late-planted corn. Okay, “dining” may not be the proper word, as they are not actually eating the kernels, but rather harvesting them to bring them back to their “hormiguera” (ant nest) for cultivation of the fungi on which they feed. The four pairs of spines on the pro-mesonotum and narrow distal antennal segments suggest this is a species of Acromyrmex, three species of which are mentioned as pests of corn in Argentina (A. lundii, A. striatus, and A. lobicornis). Of these, the individuals in these photos seem to best match AntWeb’s photos of Acromyrmex lundii, but that is just my guess.

Acromyrmex sp. poss. lundii?

Copyright © Ted C. MacRae 2012