Tiger Beetle Rearing

May 20, 2009October 10, 2011 / Ted C. MacRae / 35 Comments

I recently found an interesting website called Tiger Beetle Rearing. This website by doctoral candidate Rodger Gwiazdowski in the Joseph S. Elkinton lab, University of Massachusetts, Amherst contains a wealth of information and photographs covering equipment, techniques, and methods for rearing tiger beetles from egg to adult, with a primary focus on rearing endangered and threatened species of tiger beetles for conservation and re-release into the wild. The lab has reared a number of tiger beetle species but is particularly interested in the Puritan tiger beetle (Cicindela puritana), threatened in the northeastern U.S. After the first year of rearing, 90 2nd and 3rd instar C. puritana larvae were obtained and, as of the last update, were overwintering in individual tubes. You’ll need to register with the site with a username and password to access the site, but this is accomplished quickly and easily.

Welcome to the Hotel Cicindela!

I found this website of great interest as I begin my own efforts at rearing these beetles in the laboratory. My primary interest is in rearing larvae that I collect in the field to adulthood – adults are much more easily identified than larvae (indeed, the larvae of many species remain undescribed), and rearing field-collected larvae is one way to get around the often limited temporal occurrence that many tiger beetle species exhibit as adults. My operation isn’t nearly as sophisticated as the one developed in the Elkinton lab, but then I’m just a working stiff trying to do this (and a million other things) on the side. Despite this, I have had my first success, rearing to adulthood a larva I collected during the summer last year (see my post It’s a girl!). In addition, I currently have a number of larvae collected last fall in Nebraska and South Dakota, which I put in terraria of native soil and kept in a cold incubator during the winter. I pulled them out earlier this spring, and soon afterwards a number of larvae opened up their burrows and have been feasting on fall armyworm and corn earworm caterpillars every 2-3 days or so. The larvae were collected from a variety of habitats and soil types, including sand, alkaline seeps, and red clay banks, so I’m hopeful that the ensuing adults will represent a variety of interesting species – perhaps some that I did not encounter in the field during that trip.

Beyond this, however, I am also interested in trying my hand at cross-breeding experiments – particularly with Missouri’s unique population of Cicindela scutellaris (festive tiger beetle). I’ll need to wait until fall for this, however, since adults that are active in the field right now are sexually mature and have presumably already mated. In the fall, a new generation of sexually-immature adults will emerge and feed for a time before burrowing back in for the winter and re-emerging the following spring ready to mate. I would like to cross individuals from southeastern Missouri – representing an intergrade between the northern subspecies lecontei and the southern subspecies unicolor – with individuals from the northern part of the state that are clearly assignable to subspecies lecontei. If possible, I would also like to obtain individuals from even further south that are clearly assignable to subspecies unicolor and cross them with both the southern and northern Missouri populations. These crossing experiments may provide some insight into which of the subspecies the intergrade population is more closely related to, and it will be interesting to see how closely the progeny from the lecontei x unicolor cross resemble individuals from the intergrade population and the range of variation that they exhibit. I should mention that Matt Brust (Chadron State College, Nebraska) has done a number of these inter-subspecific crosses with C. scutellaris, with some very interesting results among the progeny.

What I can do right now is work on techniques to make sure I can get females to lay eggs and then rear the larvae all the way through to adulthood. For this, I brought back 9-10 live individuals from two localities of the intergrade population encountered on my recent trip to the southeastern lowlands. I put equal numbers of males and females from each locality into separate terraria – each filled with native soil and a hydrophilic polymer gel made of anionic polyacrylamide. The beetles, who normally obtain moisture from their food or by “chewing” moist soil, chew instead on the gel. This eliminates the need to maintain a water dish or cotton batting that must be changed daily in order to prevent the growth of mold and bacteria. A few of the adults in each terrarium died shortly afterwards, possibly a result of stress or dehydration during transport (the photo right shows how eagerly they imbibed moisture from the polymer gel after being placed in the terrarium), but the remainder have lived for four weeks now and have been digging burrows and feeding whenever food is offered. According to Matt Brust, C. scutellaris does not lay eggs on the surface of the soil (as does C. celeripes), but rather lays them about 1.5 to 2 inches below the surface. It takes 2-3 weeks before the eggs start hatching, so I am expecting to see larval burrows appearing anytime now. Matt tells me the key to getting eggs is to feed the adults “big-time” – thus, I have been offering fat, juicy fall armyworm or corn earworm larvae to the adults whenever they are out of their burrows. Watch this entertaining video of one adult having lunch:

Trilogy of Terror

May 18, 2009October 10, 2011 / Ted C. MacRae / 12 Comments

Last week, Alex at myrmecos tagged me with a fun new meme called These are a few of my favorite stings…. It’s simple – list the things which have stung you (biting doesn’t count), and tag three others for their tales of envenomization. Of course, being the dedicated myrmecologist that he is, Alex leads off with a most impressive list of venomous arthropods, and he selected worthy competition in buzzybeegirl and bugeric. But me? I have, for the most part, succeeded in avoiding stings by focusing on a group of insects (beetles) that never evolved such structures. My domestic list is short and mundane – honey bees, paper wasps, sweat bees, fire ants – and even those not very often. Alex, however, suspected I might have some tales from exotic lands – thus, I offer the following trilogy and tag Art, Doug, and Kolby.

Tale 1
When I made my first Neotropical collecting excursion some 20 years ago to Ecuador, I was warned by my guide about large, black ants that he called “Congas.” I later learned the species to be what many people call the bullet ant (Paraponera clavata). Now, I’m not an expert on which arthropod truly has the most painful sting, but many people knowledgeable about such matters say it is this species – and I believe them! We were camped out in Sucumbios Province east of Nueva Loja (also called “Lago Agrio”) at an Amazon forest site where recent construction had left rows of month-old slash lining both sides of a 2-km stretch of new road through the forest – can you say woodboring beetles? I roamed up and down that stretch of road, picking a wonderful diversity of longhorned beetles (Cerambycidae) and jewel beetles (Buprestidae) off the slash. At one point, I encountered a whole tree crown laying by the side of the road that required some clambering to get at the beetles crawling on its inner branches. At one point, I braced myself with my arm against a branch and immediately felt an excruciating pain. I looked at my arm and saw one of these large ants clamped onto my arm and quickly slapped it off. I really don’t think words can describe how painful that sting was, and not only did it throb for the rest of the day, but I actually felt sick for the next several days (though I still managed to keep roaming the slash rows). I don’t know if the bullet ant I captured right afterwards was the one that stung me, but I still took great delight in impaling a #2 insect pin through its thorax after I returned home.

Tale 2
Alex mentioned one plant – stinging nettle (Urtica dioica, which also lines one of my favorite mountain bike trails), but I’ve also had a run-in with a much more formidable plant in Mexico. Mala mujer (Cnidoscolus angustidens), which translates as “bad woman” in Spanish, deserves all the respect you can give it. Reported to be one of the most painful stinging nettle-type plants known, it grows commonly from the arid southwest down into the dry, tropical thorn forests of southern Mexico where my colleague Chuck Bellamy and I have made several trips in recent years to search for jewel beetles. One quickly learns to recognize this distinctive euphorbiaceous plant by its green palmate leaves with white veins and thick covering of yellow, stinging trichomes. Unfortunately, in my zeal for beating buprestids from Leucaena diversifolia (netting several of the rare Pelycothorax tylauchenioides and a now paratypical series of what was then an undescribed species of Agrilus), I forgot to maintain my lookout for this common understory plant and got a swipe across the knuckles. Not only did the extreme pain last for hours, but my ring finger began swelling so worrysomely that we stopped in a hospital looking for somebody to cut the ring off. My poor Spanish brought me no sympathy (or service), but fortunately the swelling began subsiding that evening and I didn’t lose my finger. I did, however, live with a rash for the next several days that developed into a hard, purple skin discoloration for the next several weeks. Bad woman, indeed!

Tale 3
I debated whether to include this experience, but the terror was real so here it is. I wrote about it recently in an article called “Dungers and Chafers – a Trip to South Africa” that appeared in the December 2008 issue of SCARABS Newsletter. Enjoy this excerpt:

After arriving at the park [Borakalalo National Park, North West Province], I could hardly contain myself – I was so anxious to start collecting… We drove through the park for a little bit looking for a good spot to pull over and begin the hunt. After finding such a spot, I grabbed my trusty beating sheet and began doing what I have done so many times before – walking up to a tree, giving a branch a whack with the handle of my net, and hoping to see some prized buprestid laying on the beating sheet. The habitat was ideal for this – dominated by low, spreading acacias such as Acacia tortilis and A. karoo. Buprestids love acacias! I had already learned this in my travels through the American desert southwest and down into Mexico and South America – surely it was the same in South Africa. The first whack yielded nothing – typical. Even when collecting is good, buprestids are never “dripping from the trees,” and often one must literally beat dozens and dozens of trees to really get a good idea of the diversity and abundance of buprestid species that are active in a given area. I whacked a few more trees, with similar results. I then spotted one particularly large acacia tree – something about it said, “beat me!” I walked over to it and gave a branch a whack. All at once, it seemed as though the world was exploding! The air was suddenly abuzz with dozens of large, flying insects, whirring and swirling all around me. My first thought in that initial moment of terror was that I had whacked a hornet’s nest – who knew what kinds of deadly, venomous wasps one might encounter in Africa? Instinctively I ducked and started running, but within a few moments I realized that I was not being chased. Cautiously, I sneaked back towards the tree (after stuffing my heart back down my throat) and realized that they were not hornets after all, but instead beetles. I looked more closely and saw that the tree was literally alive with dozens and dozens of large, green cetoniines resembling our own green June beetle, Cotinis nitida (L.), which seemed to be attracted to the small, white blooms that covered the tree in profusion. I netted a few of the beetles, which I would later determine to represent the common savannah species Dischista cincta (de Geer) (Photo 2). Such was my welcome to Africa, where it seemed the trees literally are ‘dripping’ with beetles!

Photo 2. Disticha cincta (de Geer)

Saving endangered species with herbicides

May 15, 2009October 10, 2011 / Ted C. MacRae / 25 Comments

The latest issue of Cicindela (a quarterly journal devoted to tiger beetles), which arrived in my mailbox last week, features an article coauthored by my good friends Kent Fothergill and Kelly Tindall of Portageville, Missouri, along with lead author Stephen Bouffard of Boise, Idaho (Bouffard et al. 2009). The article reports the results of a vegetative management pilot test for using herbicides to restore habitat for the critically imperiled St. Anthony dune tiger beetle, Cicindela arenicola. This species is endemic to Idaho, primarily the St. Anthony Dunes area in the southwestern part of the state (Pearson et al. 2006), and like the Coral Pink Sand Dunes tiger beetle (Cicindela albissima, recently covered in this post) it is restricted to sand dune habitats that are threatened by a variety of land-use practices, including motorized vehicle use, livestock trampling, intentional stabilization of dunes by grass seeding, conversion of dune habitats to agriculture, and disposal of public lands by transfer to private ownership (Idaho State Conservation Effort 1996).

Bouffard et al. conducted their study at Minidoka National Wildlife Refuge in southern Idaho. Cicindela arenicola was recorded on small remnant sand dunes within the refuge during the mid-1990’s but had not been detected in more recent opportunistic searches. The authors noted that the sand dunes appeared to have become overgrown with the invasive annual grass, downy brome (Bromus tectorum). Their study comprised three elements: 1) herbicide treatment on dune habitats to reduce downy brome density; 2) surveys of treated versus untreated plots during the following season to assess the efficacy of the herbicide in reducing downy brome density and any effect it might have on native vegetation, as well as the presence of C. arenicola; and 3) laboratory bioassays to evaluate the acute toxicity of herbicides on a surrogate tiger beetle species, Cicindela repanda (common shore tiger beetle). The laboratory bioassays were necessary, because toxic effects by a herbicide against tiger beetles would negate its potential usefulness for habitat improvement. For the herbicide treatment plots, Imazapic (trade name Plateau^®) was selected because of its effectiveness against downy brome, minimal effects on native vegetation, and low toxicity to animals, including insects. Imazapic is labeled for control of downy brome and for use on rangeland. A nonselective herbicide, glyphosate (trade name Touchdown^®) was also evaluated in the laboratory bioassay, even though it was not used in the field test, because glyphosate-based herbicides also have low animal toxicity and have been shown to be effective in assisting the establishment of native plant species in prairie restorations.

The authors were successful in observing live adult C. arenicola in both of the test plots where adults of this species were last seen in the mid-1990s. Moreover, larval burrows – putatively representing this species – were also noted in the plots. No adults or larvae were seen in a third plot; however, no previous records of the species exist in the area where that plot was located. They noted the presence of residual downy brome stems from the previous season’s treatment in the sprayed plots but no new growth, while the untreated controls exhibited extensive new downy brome growth. More importantly, no negative impacts on native vegetation – principally rabbitbrush (Chrysothamnus sp.) and Indian ricegrass (Achnatherum hymenoides) – were noted in the sprayed plots. The third plot had only a light downy brome invasion prior to treatment, and no apparent negative effects were observed on the native bunchgrasses, rabbitbrush, and sagebrush (Artemisia tridentata) in this plot after treatment. In the laboratory, neither imazapic nor glyphosate showed evidence of acute toxicity against the surrogate tiger beetle, C. repanda.

While the use of herbicides for conserving endangered species may seem counterintuitive, this study demonstrates a potential use for herbicides in restoring and improving sand dune habitat for a critically imperiled species of tiger beetle. Herbicides that are effective in reducing invasive annual grasses with minimal effects on both native vegetation and tiger beetles could greatly facilitate habitat management for a number of critically imperiled western U.S. sand dune tiger beetles besides C. arenicola, including C. albissima in southwestern Utah, C. waynei (Bruneau tiger beetle) in western Idaho, and C. theatina (Colorado Great Sand Dunes tiger beetle) in southern Colorado. Where vegetational encroachment presents a threat to critical sand dune habitat, broad spectrum or grass selective herbicides may offer an effective and convenient alternative to habitat restoration. Additional research will be needed to determine if repeat applications of herbicides will be necessary to prevent reinvasion, and if so with what frequency, as well as the chronic or behavioral effects of herbicides on both larval and adult forms of the insects targeted for conservation.

I thank Kent Fothergill for allowing me to use his beautiful field photograph of C. arenicola, which also graces the cover of the current issue of Cicindela.

REFERENCES:

Bouffard, S. H., K. V. Tindall and K. Fothergill. 2009. Herbicide treatment to restore St. Anthony tiger beetle habitat: a pilot study. Cicindela 41(1):13-24.

Idaho State Conservation Effort. 1996. Habitat conservation assessment and conservation strategy for the Idaho Dunes Tiger Beetle. Report No. 7, Boise, ID.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

Now you see me…

May 11, 2009October 10, 2011 / Ted C. MacRae / 12 Comments

…now you don’t!

In a previous post, I lamented the fact that I had never actually seen a live antlion larva, or doodlebug (family Myrmeleontidae). Lovers of sand, I’ve seen their famous pitfall traps many times, especially in recent years as I’ve searched sand habitats for my beloved tiger beetles. Occasionally, I’ve stopped to jab my knife under a pit, give it a quick flip, and search the freshly turned sand for the maker of the pit – never seeing anything. It never bothered me much either – there were always beetles to catch! Two weeks ago I returned to the sand prairies of southeastern Missouri to look for additional sites for Cicindela scutellaris (festive tiger beetle), and as we searched one particular site on the Sikeston Sand Ridge I once again saw the characteristic funnel-shaped pits amongst sparse vegetation in the sandy soil. I decided this time I needed to give it a good effort – how can any self-respecting entomologist accept not having ever seen a live doodlebug? As I’d done many times before, I kneeled down, gently put the tip of the knife about an inch away from the edge of the pit, and then jabbed its full length assertively into the sand and under the burrow and flipped it over. Like previous times, I studied the turned sand and saw nothing. I stirred the sand gently with the tip of the knife and studied it again – nothing. I tried another burrow – again, nothing. I decided right then and there that I was doing something wrong – I could not simply be picking ’empty’ pits. I continued staring at the turned sand, and then I saw movement – I looked closer, and it seemed as though the sand itself was moving. At last I made out its outline – I had finally succeeded in finding a doodlebug! I dug up another burrow, and knowing what I was looking for this time I had no problem quickly locating the little creature. I watched it as it lay motionless – perfectly camouflaged by its color and with sand grains sticking to its body, and chuckled as it buried itself almost instantly with a quick, backwards shuffle into the sand. Who knows how many doodlebugs I’d successfully dug up in the past, completely overlooking them as they lay disguised and motionless in the sand.

More than 100 species of antlions, representing at least 19 genera, live in the Nearctic Region, although much of this diversity occurs in the southwestern U.S. and Mexico. Despite the commonly drawn association between antlions and pitfall traps, in North America only those in the genus Myrmeleon actually exhibit this behavior. This larva dug a pit and so must represent a species of Myrmeleon – perhaps M. immaculatus, a common species in North America and one whose adult I observed last fall on a nearby sand prairie remnant. Species in other genera have free-living larvae that hide under objects or roam underneath the sand, from where emerge briefly to hunt for prey.

For those interested in learning more about antlions, Mark Swanson has an excellent website called The Antlion Pit.

REFERENCE:

Swanson, M. 1996. The Antlion Pit: A Doodlebug Anthology. http://www.antlionpit.com/

Body Invaders

May 9, 2009October 10, 2011 / Ted C. MacRae / 9 Comments

In keeping with the parasitic theme I established in my last two posts, I happened upon this brief video promotion for a National Geographic special called In the Womb: Extreme Animals which will air this Sunday (May 10). The video features the offspring of a parasitic wasp (Cotesia glomerata) that has injected her eggs into a caterpillar — and now they’re ready to emerge! It’s a fascinating study of parasitoid-host relationships, filmed incredibly from inside the caterpillar! Watch the whole video for the wicked, surprising ending.

Viewing tips: after beginning play, click on “HQ” in the lower right corner to view the video in high quality. Or, click on the video itself to be taken to YouTube, where you have the option to watch the video in HQ and in full screen mode (2nd button from the lower right corner). You will be amazed!

Vodpod videos no longer available.

more about “Body Invaders“, posted with vodpod

Tip of the hat to Adrian, who posted this yesterday (but I really did find it on my own).

Newly emerged rabbit bot fly

May 8, 2009October 10, 2011 / Ted C. MacRae / 15 Comments

First things first – congratulations to Mark Deering (Sophia Sachs Butterfly House, right here in St. Louis) and Rod Rood (Washington State University) for correctly identifying yesterday’s “What the heck?” as the cast puparium of an oestrid bot fly. Mark eventually staked his claim on the genus Cuterebra, and Rod as well included this genus in his short list. They are more astute naturalists than I – had I not found the newly emerged adult right next to it, I doubt that I would have known or figured out what it was. Thanks also to the many other people who played the game – most were united in thinking it was some kind of insect, with many noting its distinctly abdominal appearance. It seems, at least among my readers, that shed insect cuticle is a more popular quiz subject than plants.

I encountered this individual on open sandy ground while searching for my beloved southeastern Missouri festive tiger beetles. When I first saw the adult, it was on its back on the ground, feebly waving a couple of legs in the air. I at first thought it was some kind of clumsy beetle but realized what it was as I approached it. Clearly the fly was in distress, and I thought it odd that the puparium was laying on the ground next to it. Bot flies in the genus Cuterebra have among the most deliciously gruesome of all insect life histories. The ultra short-lived adults (lacking even functional mouthparts) lay their eggs near rodent and lagomorph burrow entrances, with the different species showing a fair degree of host specificity (Catts 1982). When the fly larva hatches, it migrates to the host and enters the animal’s body through a natural orifice or break in the skin. It then finds a subcutaneous location to feed, creating a cyst-like structure within a swelling of subcutaneous tissue and with a hole at the skin surface to allow respiration. Once mature, the larva exits and drops from the host and burrows into the ground for pupation. We could find no emergence hole nearby, so perhaps the puparium was exposed by rain prior to emerging and suffered some desiccation, or perhaps the adult had gotten stuck in the tough puparium and pulled it to the surface as it emerged – burning its limited energy reserves in the process. At any rate, it is rather unusual to find these things emerging with the pupal case.

Cuterebra spp. are known collectively as New World skin bot flies (formerly family Cuterebridae, but now classified as a subfamily of Oestridae). I suspected this was the rabbit bot fly (C. buccata) due to its general appearance – notably the red bands in the eyes, which is a characteristic of rabbit-infesting species. However, the genus is diverse, with 34 recognized North American species – seven of which belong to the rabbit-infesting group (Sabrosky 1986). I don’t have a copy of Sabrosky’s revision, and my efforts to locate it electronically turned up only retail listings for $70 or more. That’s serious coin for someone who really needs to stay focused on his beetles, so I sent these photographs to bot fly specialist Jeff Boettner at the University of Massachusetts. Jeff confirmed that it is indeed a Cuterebra rabbit bot and will confirm a species identity after checking his collection.

Jeff also sent the following note and interesting link:

Speaking of red eyed bots…there is one on Bugguide that a woman from NM posted. It is Cuterebra mirabilis and it may be the rarest photo on BugGuide. It’s only known from 2 previous specimens (also from NM). Its the largest of the rabbit bots. Much darker than yours.

Jeff notes that “mirabilis” in Latin means “extraordinary” – a truly appropriate name for this beautiful insect. Even though I am a devout coleopterist, I must confess – cuterebrids rock!

REFERENCES:

Catts, E. P. 1982. Biology of New World bot flies: Cuterebridae. Annual Review of Entomology 27:313-338.

Sabrosky, C. W. 1986. North American species of Cuterebra, the rabbit and rodent bot flies (Diptera: Cuterebridae). Entomological Society of America Thomas Say Foundation Monograph, College Park, Maryland, 240 pp.

Wednesday “What the heck?”

May 6, 2009October 10, 2011 / Ted C. MacRae / 39 Comments

This might be the hardest nature quiz ever – I don’t think I would’ve ever figured out what this was had I not found what I did next to it. I found it on my recent trip to look for Cicindela scutellaris (festive tiger beetle) in southeastern Missouri. Of course, now knowing what it is, the image does seem to provide enough clues about its identity – perhaps some crack naturalist will figure it out.

I’ll provide the answer with additional photos tomorrow.

A festive (tiger beetle) birthday

May 3, 2009October 10, 2011 / Ted C. MacRae / 24 Comments

Last Thursday was my birthday, and as has become my custom, I took the day off and went on my ‘Annual Season Opening Birthday Bug Collecting Trip.’ One or two of you might remember how these plans were scrubbed last year by a last minute business trip, during which I discovered Pipestone National Monument in southwest Minnesota. That experience – and the post that I wrote about it – remain high among my all-time favorites. Despite that, nothing was going to derail my plans to go collecting this year, and at 5:30 in the morning I awoke to begin what would turn out to be as enjoyable and successful a day as I could hope for. I had convinced my colleagues and long-time collecting buddies Rich Thoma and Chris Brown to take the day off as well and accompany me down to the lowlands of southeastern Missouri to search for additional localities of the festive tiger beetle – Cicindela scutellaris.

Records of Cicindela scutellaris in southeast Missouri

As far as is currently known – C. scutellaris is represented in Missouri by three highly disjuct populations in the extreme northwestern, northeastern, and southeastern corners of the state. The two northern populations are unambigously assignable to the northern subspecies lecontei, although their absence from areas further south in Missouri along the Missouri and Mississippi Rivers remains a mystery. The southeastern population apparently represents an intergrade population with influences from both lecontei and the southeastern subspecies unicolor. While this population was discovered many years ago (I first collected it in the mid-1980s), it remained known only from sand forests in Holly Ridge Conservation Area on Crowley’s Ridge. A second population was discovered several years ago on sand exposures in the extreme western lowlands near the Ozark Escarpment when Chris Brown and I began our formal survey of tiger beetles in Missouri, and last year I succeeded in locating several populations of the beetle in the critically imperiled sand prairie relicts located along the spine of the Sikeston Sand Ridge.

This year, we wanted to determine if intergrade populations also occurred on the Malden Sand Ridge – the southernmost expanse of sand exposures in the southeastern lowlands. We didn’t know if they did – presettlement sand prairies were less abundant on the Malden Ridge due to its higher soil organic content. As a result, no sand prairie relicts survived the Malden Ridge’s complete conversion to agriculture. Undeterred, I got onto Google Maps and scoured satellite imagery of the ridge and located several spots that seemed to have potential – even though they were agricultural fields, they appeared to be of sufficient expanse and with enough sand to possibly support populations of the beetle.

So, on the morning of April 23, my ‘Annual Birthday Season Opening Bug Collecting Trip’ began by meeting up with Rich and Chris and driving the 223 miles from Wildwood to Kennett to explore several locations for a beetle based only on the suggestion of a flickering computer screen. The first of these locations was a bust – there was a house constructed right in the middle of the site that wasn’t on the Google Map. Maybe the beetle occurred here and maybe it didn’t, but the last thing I wanted to do on a Thursday morning was interrupt a homeowner from their morning routine and ask them if we could collect bugs in their front yard. Besides, there was another locality just a couple miles up the road that looked equally promising. We found the spot and drove by slowly – it was an agricultural field that looked like it had been fallow for at least a short time, and although it did not look great (not as much sand as I had hoped) we eventually decided that since we were there we might as well take a look. It wasn’t long before we saw an individual near the highest part of the field, and through a couple hours of exploring and digging adult burrows we had observed a limited number of adults. Success! The landowner happened by while we were there and graciously allowed us to continue our searches. Through her, we learned that the field had been under soybean cultivation during the previous season. This was good news to learn that beetles were inhabiting sand exposures on the Malden Ridge despite its complete conversion to agriculture.

Having confirmed the occurrence of C. scutellaris on the Malden Ridge, we then began driving to the next putative locality some miles north along the ridge. Along the way, Chris spotted a rather large sand expanse in another agricultural field right next to the highway. Even though I hadn’t detected it in my Google Map search, it looked promising enough to explore, and so we did a quick U-turn and found a place to pull over. This spot can only be described as the ‘festive tiger beetle motherlode’ of southeast Missouri! Even though the field was obviously under active agricultural use, the beetles were abundant within the fairly large expanse of exposed sand within the field (photo below). We were quickly able to collect a sufficient series to document the beetle’s range of variation and set about obtaining additional photographs. I felt fortunate to be able to photograph this mating pair, which nicely illustrates the white labrum of the male (top) versus the dark labrum of the female (bottom) – one character that distinguishes this intergrade population from the similar-appearing six-spotted tiger beetle (C. sexguttata – commonly encountered along woodland trails throughout the eastern U.S., and with both sexes exhibiting a white labrum). Note also how the male is holding his legs out horizontally (a behavior I’ve seen with other mating pairs) and the more heavily padded tarsi on his front legs. The latter specialization is thought to aid in grasping and holding the female (Pearson et al. 2006), although in this instance it clearly is not serving that function, but I have not yet determined for what purpose the horizontal posturing of the front legs is all about (perhaps it is related to alarm behavior).

We completed the day by documenting the occurrence of this species on the third of only three sizeable sand prairie relicts that remain on the Sikeston Sand Ridge – a private parcel located a few miles south of the other two preserves. These observations have increased our confidence that C. scutellaris is secure in Missouri’s southeastern lowlands, and that – thankfully – no special conservation measures will be required at this time to assure its continued existence. We also now have enough material on hand to characterize the range of variation exhibited by individuals across this population. We hope this will allow a greater understanding of the relative influence of lecontei populations to the north versus unicolor populations to the south in contributing to the makeup of this population.

Since it was my birthday, it was appropriate that I should discover this “gift” next to the rim of my net after I slapped it over a mating pair of beetles. I haven’t found a large number of Native American artifacts during my time in the field, but this has to be most impressive of those that I have found – it is in almost perfect condition, with only the smallest of chips off of one of the lower corners. Edit 5/5/09: After a little research, I believe this to be a spear point from the Archaic period (12,000 to 2,500 years ago).

p.s. – my 100th post!

REFERENCE:

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

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Beetles In The Bush

Experiences and reflections of a Missouri entomologist

insects

Tiger Beetle Rearing

Trilogy of Terror

Saving endangered species with herbicides

Now you see me…

Body Invaders

Newly emerged rabbit bot fly

Wednesday “What the heck?”

A festive (tiger beetle) birthday

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