entomology

The World’s Largest Tiger Beetle

/ Ted C. MacRae / 28 Comments

Manticora scabra - male (L) and female (R) | Republic of South Africa

Some of the first residents of my new insect cabinets (see ) are also among the newest specimens in my collection. Not long ago I received a box from world tiger beetle expert David Brzoska, who had carefully chosen male/female pairs of a number of tiger beetle species from his impressive world collection and sent them to me as a surprise gift. Now, us North America-bound collectors are limited to just a few genera, e.g. Cicindela (although increasingly recognized as a cluster of several closely related genera), Tetracha, and if we’re really lucky Amblycheila and Omus (the last being one I still have not seen in the field). In the rest of the world (especially the tropics and subtropics), however, generic diversity is much higher, and coming as they did from South America, Africa, Australia, and southeast Asia most of the specimens in the sending represented new genera for my collection. While I was grateful for them all, the specimens that had me leaping for joy was this fine pair of Manticora scabra, one of the so-called “African Giant Tiger Beetles.”

Males of all Manticora spp. have asymmetrically enlarged mandibles

In the case of these beetles, the term “giant” is no exaggeration. The male specimen (above and left) measures a full 54 mm (that’s more than 2 inches, folks!) from the tip of its grossly enlarged mandible to the tip of its abdomen, and even the female at 47 mm length is substantially larger than my 38-mm long male specimen of North America’s largest tiger beetle, Amblycheila cylindriformis. While enlarged male mandibles are a common feature among many beetle groups, Manticora males feature an unusual asymmetry in the mandibles, with the right mandible always much larger than the left (itself enlarged compared to the female mandibles, and even the latter cannot be considered small).  Apparently the asymmetry represents a trade-off in natural selection—males use their mandibles not only to hunt prey but also hold onto the female pronotum during mating and subsequent mate guarding. There is positive selection pressure for larger mandible size, as males with smaller mandibles are more likely to be dislodged from the female by competing males. However, because of the large size of the species, larger male mandibles are less effective for securing normal prey items that tend to be smaller in size. If both mandibles were enlarged to the point needed to securely grip the female pronotum, the male would be unable to feed adequately, but having only one mandible fully enlarged provides sufficient grip while maintaining an ability by the somewhat smaller left mandible to grip regular prey items. A consequence of the mandibular asymmetry is that males ride “to the left” when coupled with females.

The right mandible is larger than the left mandible.

David identified these individuals as the species M. scabra, occurring throughout much of southern Africa (Botswana, Malawi, Mozambique, Republic of South Africa, Tanzania, Zimbabwe—according to Carabidae of the World). I presume the species epithet refers to the roughened surface of the elytra. There are at least two recent treatments of the genus (Werner 2000, Mares 2003); however, I have access to neither because of the exorbitant cost of these books—$247 and $433, respectively (I find it rather ironic that the recent explosion of book-sized treatments of “large” beetles has resulted in publications priced so high that they are inaccessible to most professional entomologists).

Female mandibles are nonetheless impressive despite their smaller size.

I made a trip to South Africa in 1999 and had hoped to see these beetles for myself, but unfortunately this did not happen. Perhaps part of the problem was my impression of these beetles as nocturnal hunters—the prevailing ‘wisdom’ at the time. My field partners and I made several nighttime forays in the semi-arid bushveldt where we were camping, using flashlights to scan the ground for any large black beetles we could find moving about. We found numerous tyrant ground beetles (family Carabidae, genus Anthia) and a diversity of tok-tokkies (family Tenebrionidae), but no Manticora tiger beetles. Shortly after that trip, Oberprieler & Arndt (2000) published an informative summary of the biology of several Manticora populations in South Africa, their most notable finding being that adults are opportunistic diurnal predators that hunt by smell rather than nocturnal visual hunters. Perhaps someday I’ll have another opportunity to visit South Africa and see Manticora adults in the field, but until that time I’m happy to have these two specimens residing in my cabinet.

My sincerest thanks to David Brzoska for these sending me these fine specimens and for the many additional kindnesses he has extended to me during the past few years.

REFERENCES:

Mares, J. 2003. A Monograph of the Genus Manticora. Taita Publishers, 205 pp.

Oberprieler, R. G. & E. Arndt. 2000. On the biology of Manticora Fabricius (Coleoptera: Carabidae: Cicindelinae), with a description of the larva and taxonomic notes. Tijdschrift voor Entomologie 143:71–89.

Werner, K. 2000. The Tiger Beetles of Africa (Coleoptera, Cicindelidae) Volume I. Taita Publishers, 191 pp.

Copyright © Ted C. MacRae 2012

Of Bots and Warbles

/ Chris Brown / 14 Comments

As an undergraduate at Truman State University during the mid-90’s I was part of a small mammal research group led by Dr. Scott Ellis.  My focus was on flying squirrels, but others in the group studied mice.  There were always opportunities to help my colleagues trap mice, and that is where I first encountered bot flies (Oestridae: Cuterebra spp.).  It was common for the live trapped mice to be infected with bot fly larvae, or bots, developing just under the skin of the host.  You might expect a fly parasite of a mouse to be relatively small but that is not the case with bot flies.  The bots cause a grotesquely large growth (or warble), and Cramer and Cameron (2006) report that a single bot can weigh as much as 5% of the host body weight.  That’s like a 150 lb guy having a 7.5 lb growth!  One unfortunate mouse that comes to mind had a warble on its head which caused its eye to bulge out.  I hate to make light of that poor mouse’s condition, but I distinctly recall that the bulging eye made it look as if it was continually surprised.  That said, Cuterebra fontinella infections are not thought to have a negative impact on white-footed mice, and in fact some studies have found that infected mice actually live longer than their non-infected neighbors (Cramer and Cameron 2006).  This relatively benign relationship between host and parasite is also the case in general with other species of Cuterebra, which is attributed to the long evolutionary history shared between the parasite and a single or very few closely related hosts (Catts 1982).  Negative impact or not, I was glad that I didn’t have to worry about bot flies infecting me, at least while I was in temperate Missouri.  Of course I had heard plenty of stories of humans being parasitized in the tropics by the human-attacking Dermatobia hominis, and they didn’t sound like very pleasant experiences.  My favorite story involved the person that had a bot in their ear that just about drove them crazy because they could hear the bot any time it changed positions.  Actually the Slansky article discusses the more negative interaction between D. hominis and its host, and this has been attributed to the less specialized relationship between the parasite and any one host because D. hominis has a broad range of hosts. 

Dermatobia hominis actually employ another insect to deliver its eggs to the host!  They lay eggs on mosquitoes or other blood-feeding Diptera for subsequent transfer to the host.  This makes a lot of sense from my point of view as a potential host—the adults are huge (bumble bee size), and I sure would be wary of one approaching me.  But mosquitoes, now there’s an idea—they are very adept at finding their hosts and are inconspicuous enough that they just might be able to get in close enough to allow the body heat of the host to stimulate the hatching and deposition of a bot.

There are other species of Cuterebra, and each is host specific to some degree.  Cuterebra abdominalis (Fig. 1) and Cuterebra buccata are both specific to lagomorphs (rabbits).  No doubt male tree squirrels and chipmunks get a little nervous every time they hear the species name of their bot fly—“emasculator”.  The species name originated from the observation that the warbles were often located near the genitalia of the squirrels, which prompted the idea, given the impressive size of the warble, that there must be an impact on the reproductive ability of the afflicted squirrels.  Luckily for the squirrels, research has demonstrated that the species name is a misnomer (Catts 1982).

Figure 1. Cuterebra abdominalis, a rabbit bot fly

I knew nothing of the adult Cuterebra at the time I saw the parasitized mice, but that changed when Ted MacRae netted an adult rabbit bot fly, Cuterebra buccata, while we were looking for tiger beetles in northeastern Missouri.  In May of 2006, my wife Jess and I came across an adult C. abdominalis on the edge of a glade at Shaw Nature Reserve near St. Louis, and it is this photo that I discuss more below (Fig. 1).  The only other encounter was from southeastern Missouri in April of 2009 when Ted again found a rabbit bot fly, and this individual had only recently emerged from its puparium (Figs. 2 and 3– See Ted MacRae’s previous post from 2009 on this exact same fly).  All told, that’s only three encounters with adult bot flies from countless hours spent in the field, so my experience is that adult bot flies are rarely encountered.

Figure 2. Newly emerged rabbit bot fly, Cuterebra buccata

Figure 3. Newly emerged C. buccata with shed puparium



The image in Figure 1 represents well the type of photographic opportunity that I look for because it readily leads into various side stories.  Here are some examples: 

1) Amazing natural history—you just can’t make this stuff up.  The Catts review article cited discusses numerous other aspects of bot fly natural history in addition to the discussion above.  For example:

  1. Cuterebra spp. are thought to oviposit in the host habitat where the eggs await close passage of a host.  As with the D. hominis, the body heat of the host stimulates the eggs to hatch. The first instar larvae enter the host through an existing orifice or wound and then travel through the host to find a suitable subcutaneous location to create a warble.  Here, the larva molts to the second instar and continues to draw nourishment from the host.  Cuterebra larvae feed on fluids of the host as opposed to feeding on actual tissue, which would be more damaging to the host.
  2. The larvae spend roughly one month in the host.  Upon completion of the third instar, the larva exits the host, digs into the soil, and pupates.  Bot flies overwinter as pupae.
  3. Adults do not feed and are relatively short-lived.  Their attention is focused on the serious business of reproduction. 

2) Mimicry.  As you can see from the image, C. abdominalis very much resembles a bumble bee.  This image is great for presentations because it captures the attention of grade school kids.  I include this image at the end of a series of slides containing images of bees and wasps alongside the flies that mimic them.  Kids become very engaged and have a lot of fun trying to guess which images represent the models and which represent the mimics.  By the end of the series the kids have become pretty savvy about picking out the imposters but I present this image last and C. abdominalis is so bizarre that it always stumps the audience.  The kids become even more captivated by the discussion of how bot flies make a living.

3) Insect photography technique.  It’s thrilling to find new insects, but the experience can quickly turn disappointing if the insect flies off never to be seen again just as you begin to approach it for a photograph. That would have been the case with my encounter with C. abdominalis if I didn’t have a companion with me in the field.  I was lucky to have my wife, Jess, with me on this hike.  She kept an eye on the fly as I moved in for pictures.  Once or twice it flew at my approach, and Jess was able to keep track of it so I could try again.  Ted and I have also acted as spotters for one another, and this has made the difference between getting the pic or not.

4) Great location.  We encountered C. abdominalis on the edge of the scenic glade that slopes away from the Trail House at Shaw Nature Reserve in Franklin County, Missouri.  It’s always fun to revisit certain places and get to know them and the photographic opportunities they provide.  The Nature Reserve is one such place for me.  It offers countless opportunities for insect photography close to St. Louis due to a wide variety of habitats including prairie, glade, forest, wetland, and riparian areas. 

REFERENCES:

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

Cramer J. and G. Cameron. 2006. Effects of bot fly (Cuterebra fontinella) parasitism on a population of white-footed mice (Peromyscus leucopus). Journal of Mammalogy 86:1103–1111.

Slansky, F. 2007. Insect/mammal associations: Effects of cuterebrid bot fly parasites on their hosts. Annual Review of Entomology 52:17–36.

Copyright © Christopher R. Brown 2012

MacRae Entomology Museum Expansion

/ Ted C. MacRae / 30 Comments

Badly needed drawer space is provided by these gorgeous, antique, hand-made, wooden insect cabinets.

Every five years or so I find myself facing the same dilemma—too many bugs and not enough space to keep them. Each time this occurs, I go through the same thought process trying to decide the best way to solve the problem. Do I create new space by buying new cabinets, or clear existing space by donating “excess” material? If money was no object it would be the former. However, money is an object—a new, premium 25-drawer cabinet costs more than $1,000, not to mention another $400 for the drawers to fill it (if I build them myself—3 times that amount if I buy them already made). In my younger, more care-free days I got away with plunking down this kind of money several times, eventually assembling my current battery of three half-size and three full-size cabinets holding a total of 111 Cornell drawers fully stocked with unit trays. These days, however, there are kids to feed and college costs looming on the horizon. I just can’t swing that kind of dough.

Each cabinet came complete with 10 hand-made, wooden, glass-topped drawers.

The alternative, however—donating away part of my collection, is equally unattractive. I’ve been collecting insects for most of my life, so it’s more than just a hobby—it’s a part of me. Nevertheless, I am able to draw a distinction between a working collection and a hobby collection, and for the most part mine is the former. I have a few “hobby” taxa like treehoppers and leaf beetles and such, and I’ve already made a number of donations from these groups over the years. However, the bulk of my collection—and hence drawer space—is taken up by just three taxa; jewel beetles, longhorned beetles, and tiger beetles. Not only are my research activities in these three groups ongoing, but a considerable amount of the material in these groups consists of voucher specimens for my publications. I just can’t think about divesting myself of material in these groups, at least not at this point in my life. Besides, pulling material for donation is, in itself, a long and very time-consuming process that I would not look forward to.

I’ve actually been debating my options for the past couple of years now, watching nervously as my inventory of specimens housed in temporary cardboard boxes started to balloon from the successes of the past several years of collecting. Temporary boxes are bad—not only is it impossible to integrate the specimens into the organization of the main collection, but they remain vulnerable to that dreaded pest of insect collectors around the world; DERMESTID BEETLES! (The one beetle I don’t like!) The likelihood of having specimens damaged by dermestids is directly proportional to the number of temporary boxes that must be checked periodically looking for any evidence of their presence. I’ve been hit by dermestids more than once, and with the number of temporary boxes that I currently have (more than 50) it has become almost impossible to monitor them frequently enough.

Unit trays designed for Cornell drawers fortuitously fit nicely inside the custom-sized drawers.

Of course, patience is a virtue, and my reward this time for not acting too rashly came in the form of an email sent to the members of our local entomology group by Mark Deering, Director of the Sophia M. Sachs Butterfly House just a few blocks from my office. Mark was an avid butterfly collector in the past but has divested much of his collection in recent years and, as a result, no longer needed the cabinets and drawers he was using to store his collection. The list of items he had for sale included a few Cornell cabinets with drawers, ostensibly perfect for my needs, but it was the last item in the list that caught my eye—several antique, hand-made, wooden, 10-drawer cabinets with drawers. Now, I love my Cornell cabinets—they provide state-of-the-art (albeit industrial-looking) protection for my collection. However, there is something appealing about hand-made, wooden insect cabinets. I can almost see John L. LeConte and George W. Horn themselves standing next to one and pulling a drawer to have a look at its contents. I quickly contacted Mark and made arrangements to look at the cabinets. Mark explained that they were part of a 40-cabinet set housing a collection of pierid butterflies that eventually found its way to the Smithsonian Institution… yes, the Smithsonian (such history!). He had gotten ahold of seven cabinets and was now selling them for a very reasonable price. The cabinets were gorgeous, and it didn’t take long for me to do the math; I could afford to buy three cabinets with drawers for a fraction of what a 25-drawer Cornell cabinet with drawers would cost. That’s 30 drawers total, each with almost as much space as a Cornell drawer.

Drawer 1 of my tiger beetle collection.

I picked up the cabinets a few days later and spent the next two days rearranging furniture in my ‘museum’ to create the perfect showcase spot, cleaning the glass on each drawer (both sides), and transferring my tiger beetle collection into the first cabinet (drawer 1 of which is shown at right). Despite their age several transfers of ownership, the finish is still in very good shape with only minor nicks and scratches that add a sense of history yet don’t detract from their attractiveness. Especially pleasing was the discovery that the Cornell unit trays I use for my collection fit almost perfectly in the drawers (just an annoying empty spot in the upper right corner—this can probably be fitted with a California Academy-sized unit tray, perhaps for holding insect repellent blocks since the drawers and cabinets are not as air-tight as my modern Cornell cabinets). I’ll probably move the rest of my “hobby” taxa into the remaining drawers to free up the Cornell cabinets completely for exclusive use in housing my Buprestidae and Cerambycidae. That will take some time, but it’s a good problem to have. My only fear is that after I move things around and incorporate all of my backlogged material, I will have once again used up all of the newly available drawer space and find myself facing that same dilemma that I face every five years or so!

Perhaps a little teaser is in order—one of the species in the drawer shown at right will be the subject of an upcoming post—can you guess which one? Also, 2 BitB Challenge points to anyone who can correctly identify the country shown in the map behind the drawer.

Copyright © Ted C. MacRae 2012

Pollen Bath

/ Ted C. MacRae / 23 Comments

Spintherophyta (?) sp. in flower of Abutilon pauciflorum | Buenos Aires, Argentina

One of the smallest insects I saw during my latest visit to  (Buenos Aires, Argentina) was this tiny leaf beetle (family Chrysomelidae) feeding in the flower of a malvaceous plant that I take to be Abutilon pauciflorum. At only ~4 mm in length, it could have easily gone unnoticed had I not noticed there were several feeding in flowers in a small, localized area. The best I could come up with for an ID was subfamily Chrysomelinae due to their globular shape, although the small size didn’t seem right. Turns out I’d forgotten to consider the Eumolpinae, which also contains globular species that are usually much smaller than those in the Chrysomelinae, and according to leaf beetle specialists Shawn Clark and Ed Riley this is likely a member Spintherophyta or a closely related genus.

Covered with tasty, sticky pollen!

Although there are only four species of Spintherophyta in North America (Schultz 1976), and of those only S. globosa is widespread and commonly encountered, the diversity of the genus explodes in the Neotropics (Blackwelder 1946 lists 71 species). Accordingly, neither Shawn nor Ed were brave enough to venture a guess as to which species this might represent. I should probably defer to their good sense, but part of me wonders if that coppery pronotum might suggest S. cupricollis—one of only two species in the genus listed by Blackwelder (1946) for Argentina.

REFERENCE:

Blackwelder, R.E. 1946. Checklist of the coleopterous insects of Mexico, Central America, the West Indies, and South America. Bulletin of the U. S. National Museum 185:551-1492.

Schultz, W. T. 1976. Review of the genus Spintherophyta (Coleoptera: Chrysomelidae) in North America north of Mexico. Annals of the Entomological Society of America 69(5):877–881.

Copyright © Ted C. MacRae 2012

A Living Jewel – Madecassia rothschildi

/ Ted C. MacRae / 12 Comments

In North America, beetles in the family Buprestidae are commonly referred to as “metallic woodboring beetles.” This may be a perfectly adequate name—accurate and descriptive, but it’s also a bit dry and not terribly imaginative. Personally, I much prefer the moniker given to these beetles by the rest of the world—”jewel beetles!” No other name better captures the essence of these dazzling insects—brilliant, sparkling, even gaudy in coloration and with the most exquisite of surface sculptures, and no other group of buprestids better typifies jewel beetles at their most extreme than the great tribe Chrysochroini—the ‘‘classic’’ jewel beetles! Members of this tribe are found throughout the world (Chalcophora, Texania, Lampetis and Dicerca are the most familiar North American genera) but reach their zenith in the ancient rainforests of Africa and southeast Asia—big, beautiful beetles with screaming iridescence of green, red, yellow and blue. Living jewels!

I have a fair number of chalcophorines in my collection, and among the more recent acquisitions is this fine specimen of the species Madecassia rothschildi. One of a pair of specimens given to me by friend and world buprestid-expert Chuck Bellamy, this larger of the two measures a whopping 45 mm in length (that’s almost 2 inches, folks!), surely near the top end of the range for this genus and paling only against such giants as Euchroma and Megaloxantha. The reddish-brown eyes on a brilliant green head, turquoise legs and white-flecked, wine-colored elytra are enough to make it stand out, but it is the distinctive yellow-lime “false eyes” that made me do a double-take when I first laid eyes on them after opening the box. A closer look at the eye spots reveals the yellow-lime area to be densely pulverescent.

Madecassia rothschildi and the two other species placed in the genus all hail from Madagascar (Bellamy 2008). This particular species must be rather common despite the well-chronicled disappearance of Madagascar’s native forests, as a quick Google search of the species name (or its older synonym, Lampropepla rothschildi) brings up a multitude of web sites for commercial insect dealers with this species in stock. The combination of its size, coloration, and availability must make it a popular item among philatelic collectors, and although I’m not a big fan of buying insects, I can understand the desire to purchase something as spectacular as this.

I’ll be the first to admit that these photos aren’t nearly as striking as Gianfranco Merati‘s photos of Polybothris sumptuosa, but they do well illustrate the iridescence that is common to these beetles. Iridescent coloration is due not to pigments in the exoskeleton, but rather the physical properties of different layers in the insect cuticle that reflect light of specific wavelengths in different directions (hence, resulting in apparent color shifts depending on the angle at which the subject is viewed).

Despite its commonness, it seems that virtually nothing known about the life history of this species or the host plants that it utilizes. Records in Madagascar are all from the south (Bellamy 2006), but all other references to this species consist exclusively of catalogue listings. A large, conspicuous, abundant species such as this almost begs for ecological studies—the “eye spots” can be presumed to function in predator avoidance, but how? What is the purpose of the dense brush of hairs inside the labrum (upper lip) and next to the mandibles, and why is the labrum itself so acutely emarginated? Adults are largely reproducers, not feeders—do these structures serve some other function not related to feeding? What about the dense covering of “pits” over most of the body surfaces—presumably they contain chemoreceptors for smell, but what? Host plant volatiles? Mates? Humidity? So many questions, so few answers. Imagine the even greater paucity of knowledge that exists for its smaller, less conspicuous relatives that also make their homes in the forests of Madagascar (most of them probably not adapting as well to the man-induced changes of the past century).


Congratulations to Tim Eisele, whose 13 pts not only nets him the win in Super Crop Challenge #11 but also moves him up to 2nd place in the overall standings for BitB Challenge Session #5 with 29 pts. Mr. Phidippus‘s 12 pts  just missed the win but keep him in well in command atop the overall standings at 43 pts. Strong showings by Dorian Patkus (11 pts) and Dennis Haines and Roy (10 pts each) also keep them in the overall hunt with 20, 25 and 28 pts, respectively. I suspect the top spot is now a lock, but it looks like we’ve got a real battle brewing for the remaining podium spots. There will be at least one more challenge in the current challenge session, and for the first time I am considering consolation prizes to the final 2nd and 3rd podium spots as well, so everybody will want to make sure they participate in the next challenge.

REFERENCES:

Bellamy, C. L. 2006. Insecta Coleoptera Buprestidae de Madagascar et des îles voisines. Catalogue annoté. Faune de Madagascar 92:1–267.

Bellamy, C. L.  2008. World catalogue and bibliography of the jewel beetles (Coleoptera: Buprestoidea),  Volume 1: Introduction: fossil taxa; Schizopodinae; Buprestidae: Julodinae—Chrysochroinae: Poecilonotini.  Pensoft Series Faunistica 76: 1-625.

Copyright © Ted C. MacRae 2012

Another cover photo

/ Ted C. MacRae / 4 Comments

Issue 43(4) of Cicindela (A quarterly journal devoted to Cicindelidae) is now hitting mailboxes (my copy arrived earlier this week), and for the second issue in a row the cover features one of my tiger beetle photos. Gracing the cover this time is the recently rediscovered Cicindelidia floridana, known only from a small area in the Miami metropolitan area of south Florida, and which I was fortunate to have the opportunity to see this past summer. Because the species is regarded as critically imperiled and a likely candidate for listing as an endangered species, the precise whereabouts of its habitat have not been disclosed. So far I am one of only a few people who have had the chance to photograph it in the field.

Now, some of you may think that because I serve as Layout Editor for the journal that I can horn in and put one of my own photographs on the cover whenever I want. This is not the case, and it was only because Managing Editor Ron Huber asked me if I had anything for the issue that I supplied the photo after having just done so for the previous issue. In actuality, we encourage others to submit their tiger beetle photographs for consideration, and since a majority of U.S. species have already been featured at some point over the years we especially encourage ex-U.S. photographers to submit their photos so that we can limit repetition. Obviously, C. floridana has never been featured on the cover before now, so it was a no-brainer choice for this issue.

The issue contains two delightful papers. The first is another by Mathew Brust on the stunningly gorgeous Cicindela pulchra that discusses not only additional northern range extensions in South Dakota and Wyoming, but also the rediscovery of the species in Nebraska far from the single previously known collection record in the state nearly 100 years ago! It is amazing to me that one of North America’s most conspicuously beautiful tiger beetle species has gone undetected for so long in such a large part of its range. The second paper by Dave Brzoska and Ron Huber is a long overdue biography of tiger beetle icon Norman Rumpp, who in his professional life was a rocket scientist (literally!) and as an avocation became one of North America’s leading authorities on tiger beetles (I am proud to claim ownership of Rumpp’s nearly complete set of The Coleopterists Bulletin). In addition to numerous publications and unpublished reports on tiger beetles in the western U.S., Rumpp described 12 species and subspecies of tiger beetles—including three of the western sand dune endemics that I have featured in recent weeks (Cicindela scutellaris yampae, C. arenicola, and C. albissima). What may not be appreciated is Rumpp’s sense of humor—well, just read the paper and see!

Copyright © Ted C. MacRae 2012

“My peripatetic quest for North America’s rarest tiger beetles”

/ Ted C. MacRae / 7 Comments

This week I gave a presentation on my latest Annual Fall Tiger Beetle Trip to the Entomology Group of the Webster Groves Nature Study Society. With the exception of a brief 5 year period in the early 1990s while I lived in California, I’ve been active with this local nature study group for the past 30 years (and serving as newsletter editor since 2009). I’ve given my share of entomology presentations over the years to both professional and amateur audiences, but no matter how far I might travel or the size of the audience, I always enjoy my time with this small group of local entomologists. They are my roots—the people with whom I learned to collect and began my explorations of Missouri and beyond. We are joined not only by the bonds of common interest, but by shared experiences as well. There was a good turn out for the presentation, and my thanks to the Group for the interest they showed.

Nine days, ten states, 4,300 miles:
My peripatetic quest for North America’s rarest tiger beetles

The photographs used in the presentation have been seen in various posts here over the past few months, but I thought some may appreciate the chance to see them all together in presentation format. A PDF version of the original Powerpoint presentation can be downloaded by clicking on the link above (although with a file size of just over 18 MB a high-speed internet connection is recommended). My thanks to David Pearson, Professor of Biology at Arizona State University, for permission to include in the posted version scanned images and distribution maps from his supremely useful A Field Guide to the Tiger Beetles of the United States and Canada (the bible of North American cicindelophiles¹).

¹ If you have not yet bought this most excellent book, paperback versions can be bought new for as little as $41.74. Buy it and you’ll never fail another BitB tiger beetle ID Challenge!

If you download the presentation, please remember that all materials are copyright Ted C. MacRae unless attributed otherwise and may not be used without permission (personal use excepted) .

Copyright © Ted C. MacRae

Return to Calico Rock

/ Ted C. MacRae / 17 Comments

Sandstone glade | nr. Calico Rock, Arkansas.

Although western sand dune endemics were the top goals on my  during last fall’s Annual Tiger Beetle Trip, I started the trip by leaving St. Louis in the most unlikeliest of directions—south! No, I wasn’t trying to get to Denver without having to drive the tedious stretch of I-70 through Kansas. Rather, I wanted to take advantage of the chance to witness active adults of the Missouri/Arkansas disjunct population of Cicindelidia obsoleta vulturina (prairie tiger beetle)—perhaps my favorite of all tiger beetle species—on the sandstone glades near Calico Rock in north-central Arkansas. Widely disjunct from the main population’s eastern limit of distribution in central Texas, I’ve seen them at many locations in the White River Hills of southwestern Missouri and adjacent Arkansas over the past ten years, but never in the area around Calico Rock where they are best known from the state. I already had precise localities where I knew I could see them, as I had found 3rd-instar larvae earlier in the year (some of which had already emerged as adults), so I wanted see them and document the range of variability exhibited by adults at this southeasternmost known extent of the disjunct population’s distribution.

Cicindelidia obsoleta vulturina | nr. Calico Rock, Arkansas.

Although the adults were not quite as numerous as I have found them at certain sites in Missouri, I had no trouble finding them once I got to the area where I had collected the larvae this past June. While showing Steve Spomer our Missouri population last year, he commented that our Missouri adults seemed much less flighty than adults he had seen at Calico Rock. I must say that I agree with him, as I found the adults much more difficult to photograph than those in Missouri. To be honest, I had to stalk nearly ten individuals before the male in the photo above finally allowed me to get close to him. When adults are numerous this is not a problem, but in this case every failed attempt required several more minutes of searching for the next subject. Eventually, however, I got my mojo and started having success with the photographs.

Unlike true spring-fall species, mating occurs in fall instead of spring.

In the main population, and like other members of the genus Cicindelidia, adults are active during the summer months and exhibit the classic “summer” species life history. The Missouri/Arkansas disjunct population, however, shows a phenologic shift in adult activity to the cooler fall months—perhaps in response to the generally droughty conditions that prevail during the summer in this part of the country followed by rains during late summer and into fall. (This is one reason why I think this population may be deserving of separate subspecific status.) In this regard they appear to be “spring-fall” species, but their life history does not match true members of that group, which emerge during fall as sexually immature adults, hibernate during winter, and re-emerge during spring for mating and oviposition. Thus, one never sees adults of classic spring-fall species like Cicindela limbalis mating during the fall. In contrast, adults of this disjunct population emerge, mate, and lay eggs all during the fall before the onset of winter, then they’re done. The eggs hatch during fall and require another season or two to reach 3rd-instar and pupate during the summer for fall emergence.

Coloration likely functions in crypsis, as shown by this individual nestled in amongst moss and lichens.

When viewed as prepared specimens in a cabinet, C. obsoleta and its subspecies are among the most conspicuous of species due to their large size (in Missouri and Arkansas only Tetracha virginica is larger), olive green coloration, and bold white maculations. More than likely, however, the combination of color and markings serve a crypsis function in their native habitat. This is clearly evident with the individual in the above photograph, who had retreated to a moss- and lichen-covered rock crevice in his efforts to evade my lens. Squint your eyes a little bit, and he almost disappears! It must be similar for visually based predators such as birds and lizards.

On more open ground and from a lower angle, the beetle is much more visible.

This same individual, however, becomes quite visible when chased onto more open rock surfaces (and viewed more laterally than from above). It is common to see individuals out in the open such as this, but more often than not when alarmed they fly or run to less exposed areas, relying on their cryptic coloration to avoid detection. In fact, when I follow beetles that have evaded me to the spot where I am sure they must have landed, I often fail to see them even though I am looking almost exactly in the area where they are sitting until they start to crawl and their movement catches my attention.

A rather greenish individual tries to hide amongst lichens and shortleaf pine duff.

I have observed a great deal of variability in coloration and maculation at locations in Missouri, with individuals ranging from bright green to dull olive-green to dark green and even brown, and the markings ranging from complete to interrupted. I saw a similar amount of variability in the Calico Rock population, with the exception of brownish (which I have only seen at the northernmost localities in Missouri) and fully maculated individuals. Most of the Calico Rock individuals were dull olive-green, but the female in the above photo (trying to evade my attentions by hiding amongst lichens and pine duff) was as bright a green as I’ve seen in any individual.

A very weakly maculate individual.

As mentioned above, I didn’t seen any individuals that I would consider fully maculated, and several that I saw were more weakly maculated than any I’ve seen in Missouri. The female in the photograph above was the most weakly-marked individual that I saw, with the lateral and median bands greatly interruped—the latter nearly reduced to small discal spots.

A dark, almost blackish female.

While I did not see brownish individuals as I have seen at the northernmost localities in Missouri, I did see the occasional blackish individual—the one in the above photograph also exhibiting about the greatest degree of macular development that I observed among the adults seen. My impression now is that there are clinal patterns to the coloration and macular development in this disjunct population, with markings tending to be more developed in northern localities. With the specimens collected from this and the many other locations throughout the disjunct population’s range that I have now sampled, a more critical assessment of variability in this population may now be possible.

Beetle's-eye view of sandstone glade habitat.

It has become standard practice for me to photograph tiger beetle habitats whenever I can. However, I’ve become interested recently in trying to understand how tiger beetles perceive their own habitats. While this isn’t possible to know precisely, ground level photographs can provide at least a clue into seeing the world from a beetle’s eye. I almost find this perspective of the glade habitat more interesting than the human perspective shown in the first photograph.

The last sight that their prey sees.

There can be little doubt about what the beetles themselves look like from the perspective of their prey. The photograph above may not properly represent the image generated by an insect’s collective ommatidia, but it certainly must be just as frightening!

Copyright © Ted C. MacRae 2012