9th Annual Fall Tiger Beetle Trip: Day 1

Once again, I have embarked upon my Annual Fall Tiger Beetle Trip, this being the ninth consecutive year that I have done such a trip. Unlike previous editions, however, the quarry on Day 1 (Sept. 15) was not a tiger beetle but a longhorned beetle. Ataxia hubbardi is not uncommon in the eastern and central U.S. and breeds in the living tissues of a variety of herbaceous plants, but especially certain species of Helianthus, Ambrosia, and Silphium in the family Asteraceae. I was hoping to see a distinctive population of this beetle that is associated with prairie dock (Silphium terebinthinaceum) in the dolomite glades just south of St. Louis. This population is interesting because individuals are smaller, darker, and narrower in form than is typical for the species, and I would like very much to get some photographs of the adults, which seem most abundant in the fall, on the tall flower stalks of their host plant.

Victoria Glades Natural Area | Jefferson Co., Missouri

I first discovered the population many years ago—back in the 1980s when I visited one particular glade, Victoria Glades Natural Area, almost weekly over a period of several years. I left Missouri for a few years in the early 1990s but returned in 1995, and during my absence fire was implemented in Victoria Glades and other glades in the area as a management practice for controlling invasion by woody plants (primarily eastern red-cedar, Juniperus virginiana). While the use of fire has certainly done much to restore the glades and improve its floral diversity, it seems more than coincidental that insect abundance and diversity on the glades is only a fraction of what I observed during my pre-burn collecting in the 1980s. There are a number of beetle species that I found at the glade historically that I have not seen now for more than 20 years; one of which is this distinctive population of A. hubbardi.

Prairie dock (Silphium terebinthinaceum) – host for Ataxia hubbardi

The prairie dock plants were at the height of bloom, but the flower stems seemed shorter and the normally large, spatulate basal leaves of the plants generally smaller than typical—perhaps a result of this summer’s severe drought. How such conditions affect the beetles is unknown. The day was also rather cool due to unbroken cloud cover and light drizzle, with temperatures in the low 70s during my visit. I spent the better part of two hours inspecting the stems of every prairie dock plant that I encountered and did not see a single beetle, so it has now been 23 years—almost a quarter century—since I’ve seen this once fairly common species at the glade. Can I prove that fire management has extirpated the beetle? No—populations might have been knocked down by the drought, or maybe the adults hide on cool, cloudy, drizzly days. Still, the pattern is too consistent to ignore, and I become increasingly worried that a special feature of these glades has now been lost.

Ninebark (Physocarpus opulifolius intermedius) – host for Dicerca pugionata

On the other hand, another quite rare beetle that I encountered abundantly at Victoria Glades in the past seems to have rebounded from its long absence—the jewel beetle Dicerca pugionata. This beautiful beetle is associated with the scraggly clumps of ninebark (Physocarpus opulifolius intermedius) that hang on in the moist toe slopes of the glades. I wrote about this species earlier this year after re-discovering it in the glades; however, I couldn’t resist taking a few more photographs of this stunningly gorgeous species. This species also makes its appearance in the fall as well as spring, and in the two hours I spent searching I counted 13 beetles—more than I’ve ever seen on any one day. Interestingly, most of these were associated with a stand of plants in an area at the south end of the glade that I had never searched before and that appears not to have been subjected to fire management (cedar removal has been effected instead with a chain saw). Only a few of the beetles were found in the much more abundant plants growing in the area of the glade I am more familiar with and that has obviously been subjected to repeated burning. It’s not proof, but I’m just saying…

Dicerca pugionata on ninebark branch.

Adult beetles are colored almost precisely the same as the bark of their host plant.

More even lighting in this face shot compared to my previous attempts.

The cool temperatures and light drizzle were not conducive to much other insect activity, but while crossing the small, shallow creek that separates the south end of the glade from the main glade, the biggest male tarantula (Aphonopelma hentzi) that I have ever seen caught my attention as it crossed the creek. Situated only 30 miles south of St. Louis, Victoria Glades must represent the northeastern limit of distribution for the species, and although I once saw a tarantula crossing the road very near to this location, this is the first tarantula that I have actually seen in the glades that lie so close to St. Louis. Males are famous for their fall wanderings, presumably in search of the females that tend to stay within their burrows. This male was missing part of one of its hind legs but otherwise appeared quite healthy and robust. I hope he succeeds in finding a mate and sires many offspring and is not discovered by any of the poachers who regularly scour the glades and steal its more unusual inhabitants—the glades have already lost enough of their unique residents…

Can you find the tarantula crossing the creek? (Hint: 0.60X, 0.37Y)

Male Aphonopelma hentzi | Jefferson Co., Missouri

Copyright © Ted C. MacRae 2012

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About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
This entry was posted in Arachnida, Araneae, Asteraceae, Buprestidae, Cerambycidae, Coleoptera and tagged , , , , , , , , , , , , . Bookmark the permalink.

6 Responses to 9th Annual Fall Tiger Beetle Trip: Day 1

  1. Very nice Ted! I especially like your photo of the tarantula! I didn’t know that they occurred in MO.

    • It’s funny you like the tarantula photo best, as I took it with my iPhone. In fact, the jewel beetle photos are the only ones in this post that I took with my ‘real’ camera. It’s the first post I’ve done featuring iPhone photos.

      Tarantulas are fairly routine in Missouri’s southwestern glades, but to see one just south of St. Louis is a real treat.

      • James C. Trager says:

        We also have those lovely mygalomorphs in the SNR glades, though I usually don’t see more than one or two a year, and these almost always wandering males. — Secretive, I supppose, and maybe mostly nocturnal? Come to think of it, the last one I saw (late Sept. 2011) was out on a cool drizzly day, like your sighting. Ever eager to throw in an anty tidbit, I’ll mention that our two northern army ant species, Neivamyrmex opacithorax & N. nigrescens, strictly nocturnal in summer, may be seen on the surface on cool overcast fall days, too.
        (Note to Art: Another cool arachnid, Centruroides vittatus also occurs on the glades near St. Louis.)

        Now about fire: I, like you Ted, wish I could fathom how all the apparently fire sensitive entomofauna made it to the present, through a long history of repeated, landscape-scale fires that shaped this part (perhaps most) of temperate North America’s vegetation. In any case, observations like yours certainly point to the need for moderation in use of fire as a vegetation managment tool, now matter how energy- and labor-saving (and most would say, awesome) it may be.

        • I think we’re on the same page about fire I’m sure many species suffered local extirpations in pre-historic fires. The difference with those fires is that no matter how large they were, they were always surrounded by unaltered, unhomogenized habitat which facilitated recolonization. Ataxia hubbardi might recover like Dicerca pugionata seems to have done (or is doing), but maybe not fast enough to suit my life span.

  2. randomtruth says:

    That jewel beetle is wonderful. We have a species of ninebark (P. capitatus) here in the Santa Cruz Mountains – any idea if it hosts similar beauts?

    • Sorry, but this beauty is restricted to eastern North America. There are, however, other great species of Dicerca in California associated mostly with oaks. Willow also hosts species in this and related genera.

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