9th Annual Fall Tiger Beetle Trip: Day 3.2

My plan to retrieve beetle-infested wood in Oklahoma’s Glass Mountains has morphed from a quick stop to an all-morning affair, and by the time I loaded up the bundles it was well past noon. Fortunately, my next planned stop—Alabaster Caverns State Park—was only about a 90-minute drive, meaning I would still have plenty of time to give the area a good look. Unlike the Glass Mountains, with its gypsum-capped, flat-topped mesas rising above the surrounding landscape, Alabaster Caverns is level ground fissured by deep, rugged canyons that have eroded through the gypsum cap into the soft, underlying red clay. Nevertheless, both sites are part of the same Gypsum/Red Hills geological formation, so their associated flora and entomofauna are also similar. It was during my original visit to Alabaster Caverns back in 2009 that I found robust populations of Cylindera celeripes (Swift Tiger Beetle), and in October of the following year I discovered its previously unknown larva. My originally intent in coming here this time was to look for Cicindela pulchra (Beautiful Tiger Beetle), but since I had failed to find this species in the Glass Mountains I had little optimism that I would find it here as well. Still, it’s a beautiful park and I was anxious to see some of the canyon areas that I had not explored on previous visits, after which my trip would take a turn to the south.

Alabaster Caverns State Park, Woodward Co., Oklahoma

As I expected, no amount of searching on the flats above showed any evidence of C. pulchra, and I saw pretty much the same assortment of beetles visiting the yellow-flowered Heterotheca stenophylla (stiffleaf false goldenaster) and Gutierezzia sarothrae (broom snakeweed) blooming in profusion that I had seen on Day 2 at Gloss Mountains State Park. Since I had neglected to photograph the gray blister beetle (family Meloidae, genus Epicauta) that I was seeing so commonly the day before, I decided I should go ahead and take advantage of the opportunity while I had it. As I mentioned in my Day 2 post, these beetles were seen almost exclusively on Gutierezzia, and shown below are two of the better photos that I ended up with.

Epicauta sp. | Alabaster Caverns State Park, Woodward Co., Oklahoma

Mouthparts at 3X—love that pollen!

Another species that I saw very commonly were tiny little beetles feeding exclusively on the Heterotheca flowers. Measuring less than 5mm in length, a majority of flowers had at least one of these small gray beetles, and sometimes as many as four or five. Just based on appearance I suspected they represented something in or related to the soft-winged flower beetles (family Melyridae), and in fact they are a dead ringer for the species Listrus senilis(compare to these photos of the MCZ type specimen). This species seems to occur abundantly throughout the Great Plains (Mawdsley 1999) as far south as Texas (BugGuide). The small size of these beetles made them much more difficult to photograph, so my ‘keeper’ rate was lower than for the Epicauta beetle, but a few turned out okay:

Listrus senilis on Heterotheca stenophylla | Alabaster Caverns State Park, Woodward Co., Oklahoma

Listrus senilis at 5X—another pollen lover!

The most significant find of the day, however, was also the most unexpected—I saw numerous individuals of an Acmaeodera jewel beetle feeding on the Heterotheca flowers. Why is this so unexpected? Because throughout most of North America members of the genus Acmaeodera are almost exclusively active as adults during spring and early summer. Those occurring in southeastern Arizona are found more during July and August, a result of the summer monsoon season, but truly fall-active species are limited to a few occurring in the Lower Rio Grande Valley of south Texas. When I saw the first one I presumed it was a late season straggler, but then I saw another, and another. It was clear by their numbers that now is their activity period. I do not know what species they represent, but I took numerous photos and will post them once I have made an identification. It remains to be seen whether this is an unusual habit for a known species (more likely) or a previously unknown species (less likely, though new species of Acmaoeodera continue to be discovered routinely in the U.S.)—stay tuned!

REFERENCE:

Mawdsley, J. R. 1999. Redescription and notes on the biology of Amecocerus senilis (LeConte) (Coleoptera: Melyridae: Dasytinae). Journal of the New York Entomological Society 107(1):68-72.

Copyright © Ted C. MacRae 2012

9th Annual Fall Tiger Beetle Trip: Day 2

I didn’t mind my late start to the 9th Annual Fall Tiger Beetle Trip—my first stop on Day 1 was only ~30 miles south of St. Louis, so I would get in a good chunk of collecting on the day even though I didn’t leave the house until after noon. I didn’t find the longhorned beetle, Ataxia hubbardi, that I was looking for (and haven’t seen now for more than 23 years), but I did manage to see good numbers of the always impressive jewel beetle, Dicerca pugionata, and a very large, impressive male tarantula (walking on water!). After that, however, the trip would make a very early diversion from its original itinerary. The light drizzle that pestered me all day at Victoria Glades steadily turned to rain as I traveled south towards northern Arkansas, and checking the weather forecast further reduced my optimism as rain was predicted for the next two days. The tiger beetles that I so enjoy are creatures of the sun, and rather than spend the next two days being chased around the Ozark Highlands looking for dry ground, I made a snap call and bolted straight for northwestern Oklahoma, where I had planned to go after two days in northern Arkansas and southwestern Missouri (collecting populations of the disjunct Prairie Tiger Beetle, Cicindelidia obsoleta vulturina, for molecular analysis by a collaborator). It was hard driving—five hours on dark, rainy roads to get to Springfield for the night, and another six hours to get to my first destination; Gloss Mountains State Park. I have been here several times over the past few years, discovering resident populations of three very interesting tiger beetles: Cylindera celeripes (Swift Tiger Beetle), Dromochorus pruinina (Frosted Dromo Tiger Beetle), and Amblychelia cylindricollis (Great Plains Giant Tiger Beetle). I did not expect to see any of these species on this trip, as they are all summer species (although I did hold out hope that I might find a few stragglers, especially of the last one). Instead, I was playing a hunch that Cicindela pulchra (Beautiful Tiger Beetle) might be found here because of the similarity of the Red Hills habitat to that just north in south-central Kansas where the species famously occurs (MacRae 2006).

Gloss Mountains State Park, Major Co., Oklahoma

It was worth the drive, as driving west got me out of rain and once past Enid, OK the cloud cover began to break up. By the time of my early afternoon arrival at Gloss Mountains State Park, skies were blue and temps were in the low 70s. Unfortunately, despite these perfect conditions my hunch that C. pulchra might occur here did not prove to be true. Nevertheless, it was a fruitful day as I collected two larvae each of all three of the above tiger beetle species (including 2nd instars of the presently undescribed C. celeripes and 3rd instars of the frightfully enormous A. cylindriformis—what an impressive creature!), photographed several beetles on yellow asteraceous flowers—two of which I show below, saw another male tarantula, and found an adult female of the truly impressive lubber grasshopper, Brachystola magna, that will become my daughters’ newest pet and has already been named ‘Bertha’ by them. My wanderings through the prairie at night with a lamp on my head did not produce any A. cylindricollis adults, but the views of the Milky Way in the dark, cloudless sky above amidst the overwhelming silence of a vast prairie cloaked in darkness were nothing short of spectacular.

Caps of gypsum over soft red clay have resulted in a landscape of flat-topped mesas.

Here are two of the beetles that I photographed on the day. This first one is a soldier beetle (family Cantharidae) that is a dead ringer for Chauliognathus limbicollis. I couldn’t find any indication that this species is known from Oklahoma—all of the BugGuide photos of this species were taken in Arizona, while the admittedly outdated key to species in the tribe Chauliognathini (Fender 1964) gives only more western states (Arizona, Colorado, New Mexico and Texas) in its distribution. Still, I saw the species not uncommonly as it fed on yellow asteraceous flowers.

Chauliognathus limbicollis on yellow asteraceous flower | Glass Mountains, Oklahoma

Another beetle that I photographed on flowers of Heterotheca subaxillaris (stiffleaf false goldenaster) was this small blister beetle (family Meloidae) that seems to be a member of the great genus Epicauta. I won’t even attempt a species ID due to the size and difficult taxonomy of this genus; however, this was the only example of this species that I saw amidst abundant individuals of another solid gray species that seemed to prefer the flowers of Gutierezzia sarothrae (broom snakeweed) over H. subaxillaris.

Epicauta sp. on Heterotheca subaxillaris flower | Glass Mountains, Oklahoma

During the day, I found some trees infested with jewel beetle larvae (presumably in the genus Chrysobothris), so I will return in the morning of Day 3 to harvest the wood and bring it back to put up in rearing containers in an attempt to rear out the adults. Afterwards, I will be off to my next destination—Alabaster Caverns State Park.

REFERENCES:

Fender, K. M. 1964. Tbe Chauliognathini of America North of Mexico (Coleoptera—Cantharidae), Part 2. Northwest Science 38(3):95–106.

MacRae, T. C. 2006. Beetle bits: The “beautiful tiger beetle”. Nature Notes, Journal of the Webster Groves Nature Study Society 78(4):9–12.

Copyright © Ted C. MacRae 2012

Lytta vulnerata cooperi

Lytta vulnerata cooperi | Idaho Falls, Idaho

I had other quarry on my mind when I visited Idaho a couple of weeks ago, but I couldn’t help but pay attention to this blister beetle (family Meloidae) feeding on rabbit brush flowers for the following two reasons: 1) its spectacular and boldly contrasting black and orange coloration, and 2) my collecting partner, Jeff Huether, is an expert on North American Meloidae. My identification of this individual as Lytta vulnerata is based strictly on one line of evidence: Jeff said that’s what it is!  My further identification as the subspecies L. vulnerata cooperi is more tenuous, being based on the distinctly sculptured elytra, immaculate pronotum, and more northerly location (nominotypical individuals, at least from what I can tell looking at photos assigned to the two subspecies, have the elytra indistinctly sculptured, generally exhibit a median line or vitta on the pronotum, and occur further south).

Note distinct elytral sculpturing and immaculate pronotum

Copyright © Ted C. MacRae 2011

Mylabris oculatus in South Africa

Mylabris oculata, the CMR bean beetle, is a large, conspicuously-colored beetle in the family Meloidae (blister beetles) that I saw quite commonly during my stay in South Africa.  “CMR” refers to the Cape Mounted Rifle Corps, a police force in the old Cape Colony whose uniforms sported black and yellow bands that resemble the colors of this beetle.

Blister beetles as a whole are, of course, well known for their chemical defenses, primarily cantharidin (the active ingredient in ‘Spanish Fly’, an extract of a European species of blister beetle).  This terpenoid compound is a painful irritant, especially when coming into contact with mucous-lined membranes such as those of the gatrointestinal and urinary tracts.  Blister beetles emit body fluids containing cantharidin from joints on the legs when disturbed, giving any would-be predators a foul-tasting appetizer. As we have so often seen, insects containing such effective defenses are often aposematically colored to advertise the fact, allowing them to brazenly lumber about fully exposed during the day with little to fear.  If there ever was an insect that screamed aposematic, it is M. oculatus with its boldy contrasting black and yellow elytra and hot-orange antennae.

These beetles, however, are more than just a frustration for hungry birds, but also a serious pest of numerous ornamental, fruit and vegetable crops (Picker et al. 2002).  Large numbers of adults congregate on plants and preferentially feed on the flowers.  In the more natural settings where I was encountering these beetles, they were most often seen on flowers of Acacia spp. or (as in the above photo) Dichrostachys cinerea in the family Fabaceae.  To be honest, they became quite a source of frustration for me as well – not because of their distastefulness or pestiferous habits, but because of their role as the model in a mimicry complex.  It was the mimic that I was after, and since mimics tend to be much less common than their models, I had to look at a lot of M. oculatus to find the few specimens of the species I was after. 

Pop quiz: Can anybody name the mimic?

Back to their chemical defenses – I’ve often wondered just how poisonous blister beetles really are, especially to humans.  Here in the U.S., their main importance is as contaminants in alfalfa hay fed to cattle and horses.  Deaths from severely contaminated forage do occur, but this is dependent upon the cantharidin content of the species and their abundance within the hay.  The highest reported cantharidin content for a blister beetle is 5.4% dry weight in Epicauta vittata.  Calculations based on this figure and the lethal dose for a 1000-lb horse indicate that around 100 such beetles would need to be eaten to receive a fatal dose.  This seems to make the claim that a single beetle can kill a human a little far-fetched.  However, M. oculatus are big beetles – more than a full inch in length and bulky.  In this regard, I found an interesting tidbit at the TrekNature website.  Clarke Scholtz is an entomologist at the University of Pretoria, and when asked, “Is it true that their poison can kill a human being?”, he responded:

Yes; they are poisonous enough to kill people – especially a big beetle… The poison is very toxic and actually causes collapsed tissue. It would also depend on the weight of the person, as with any other toxin. The poison of a CMR beetle, that is dried and powdered, is sufficient to kill a 70kg human.

REFERENCE:

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

Copyright © Ted C. MacRae 2010

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