The best species name ever!

Entomoderes satanicus

Entomoderes satanicus | Ruta Nacional 20 @ km 367, San Luis Province, Argentina

This past February while traveling to see research plots in Argentina, I had the pleasure of accompanying colleague and scarab expert Federico Ocampo to San Juan Province in west-central Argentina to see some of the endemic scarabs that live in the sand dunes that dot the region. Along the way we made a quick stop at a sandy spot along Ruta Nacional 20 in San Luis Province to see what was out and about. Several interesting insects were seen, but one of the most impressive was this marvelously armoured darkling beetle (family Tenebrionidae) belonging to the genus Entomoderes—also endemic with nine species ranging from southern Bolivia to central Argentina (Flores & Roig-Juñent 1997).

Entomoderes satanicus

Stout spines and a heavily sclerotized body surely provide effective anti-predation defense…

The stout, backwards-directed lateral spines on the pronotum are as evil as any I’ve ever seen, perhaps being the the reason behind the most awesome species epithet I have ever encountered—satanicus! Actually, there was some question about whether it represented this species or another in the genus with an almost equally awesome name—draco! I wasn’t able to access the more recent, paywall-protected revision by Flores & Roig-Juñent (1997); however, a relatively recent prior work (Peña 1990) seems to confirm its identity as the former by the presence of distinct raised costae on each elytron between the lateral keel and sutural margin confirm.

Entomoderes satanicus

…but not from tiny enemies (note parasitic mite on the venter behind the right procoxa).

Surely the sharp, stout spines and heavily sclerotized, ridged body provide effective protection from vertebrate predators and perhaps also help to minimize loss of water, since all of the species are found strictly in arid habitats (Peña 1990). I did not collect the specimen, but many such heavily sclerotized darkling beetles can be difficult to nearly impossible to pin by normal means (I have actually used a hammer to help in the case of one species I collected in South Africa. Seriously!), and I’m sure this one would have been no different. For all its armoured protection, however, there still remain chinks—note the tiny, bright red, parasitic mite on the ventor behind the right procoxa in the last photo.

REFERENCE:

Flores, G. E. & S. Roig-Juñent. 1997. Systematic revision of the Neotropical genus Entomoderes Solier (Coleoptera: Tenebrionidae). Insect Systematics & Evolution 28(2):141–162 [abstract].

Peña, L. E. 1990. El género Entomoderes Solier (Coleoptera: Tenebrionidae). Boletin del Museo Nacional de Historia Natural Textos sobre patrimonio natural de Chile 37:253–259 [ISSUU].

© Ted C. MacRae 2015

Crypsis? Mimicry? Crypsimicry?

Continuing with the previous post’s theme on crypsis, here is an interesting insect that I photographed in north-central Oklahoma in late June 2014. I was checking standing and fallen trunks of large, dead eastern cottonwood (Populus deltoides) trees in Woods Co. near the Cimarron River, where just a few days earlier I had found a jewel beetle (family Buprestidae) that had eluded me for more than 30 years—Buprestis confluens. I had found only a single individual and returned to the spot in the hopes of finding more. As I searched the trunk of one particularly large, fallen tree—its trunk still covered with bark, I noticed movement but couldn’t make out right away what I was seeing. A closer look revealed the movement to be from a wasp-like insect, its antennae curiously quivering in a manner that reminded me of an ensign wasp (family Evaniidae). More careful looking, however, revealed the insect to be not a wasp, but a longhorned beetle (family Cerambycidae), which I then recognized to be the species Physocnemum brevilineum.

Physocnemum brevilineum

Physocnemum brevilineum (Say, 1824) on fallen cottonwood (Populus deltoides) | Woods Co., Oklahoma

This beetle is commonly referred to as the elm bark borer, a reference to the larval habit of mining within the bark of living elm trees, but as far as I can tell this beetle is anything but common. Like the Buprestis confluens that I had found a few days earlier, this was a species known to me only by pinned museum specimens (I’m always amazed when a woodboring beetle species is apparently common enough to warrant a common name and is said to reach pest status in some cases, yet eludes my net for decades!). At any rate, my impression based on these pinned specimens and published images was that the species is another of the many longhorned beetles that seem to mimic ants (Cyrtinus, CyrtophorusEudercesMolorchus, and Tilloclytus being among the others). Like many of these other mimics, the species is dark with small amounts of red and bears polished, ivory-colored ridges at mid-elytra to give the illusion of a narrow waist. After seeing a living individual, however, and especially its behavior—in particular the very wasp-like manner in which it moved its antennae, I’m not so sure that ant mimicry alone explains the appearance and behavior of the species.

Physocnemum brevilineum

A lateral view reveals the beetle, but is it trying to mimic an ant, or a wasp, or both?

Of course, there is no reason why it must be ant mimicry or wasp mimicry (or crypsis, for that matter). Evolution has no rule stating that only one survival strategy can be employed at a time, and if, as it seems to me, the beetle is utilizing both crypsis and mimicry—the first to avoid detection and, failing that, the second to give the potential predator pause, then there is no reason why the mimicry portion of its defense couldn’t be modeling both ants and wasps as a way to maximize an overall “nasty hymenopteran” appearance.

© Ted C. MacRae 2015

Redux: Now you see me…

Chalcophora virginiensis

Chalcophora virginiensis (Drury, 1770) | vic. Calico Rock, Arkansas

…now you don’t!

Chalcophora virginiensis

Chalcophora virginiensis (Drury, 1770) | vic. Calico Rock, Arkansas

Chalcophora virginiensis (Drury, 1770) is the largest jewel beetle (family Buprestidae) in eastern North America. This beetle is also known as the “sculptured pine borer”, and its easy to see why—its hyper-sculptured, shiny metallic body glitters like a jewel in the sunlight! This feature is typical of many species in the family and, in fact, is the source of the family’s other common name—metallic wood boring beetles.

Such dramatic sculpturing and coloration makes cabinets of jewel beetle specimens among the most beautiful in any museum, and for those who have only seen these beetles as pinned specimens in cabinets it can be hard to imagine what purpose such appearance serves. In its native habitat, however, on native host plants, the reason becomes clear. Rather than conspicuous and easily seen, such coloration actually helps the beetle to blend in with its environment and become almost invisible. Measuring well over an inch in length and possessing no other way of defending itself by biting, stinging, or even just tasting bad, these beetles would be a more than healthy snack for almost any avian or reptilian predator, and going about their activities during the day right under the noses of all these visually based predators makes finding mates and oviposition sites an even riskier proposition. For them, the best way to beat a visual predator is to become… invisible! The two photos above show just how dramatic a difference the substrate plays in allowing these beetles to practice their disappearing act. Land on the trunk of a dead or dying pine tree, its aged bark flaked and graying, and the sculpturing and coloration are a perfect match. Land, however, on a healthy tree, its resin-filled bark bright and full of color, and it suddenly becomes a sitting duck. It’s in the beetle’s best interest to be good at telling the difference between thrifty and unhealthy trees, which they do by “smelling” volatile chemicals emitted by trees under stress.

Those interested in more information on this species and its close relatives may wish to consult the recent review of the genus in North America by Maier & Ivie (2014) (see my review of this excellent paper here).

REFERENCE:

Maier, C. A. & M. A. Ivie. 2013. Reevaluation of Chalcophora angulicollis (LeConte) and Chalcophora virginiensis (Drury) with a review and key to the North American species of Chalcophora Dejean (Coleoptera: Buprestidae). The Coleopterists Bulletin 67(4):457–469 [abstract].

© Ted C. MacRae 2015

Flower ants? Check again!

Last spring while hiking the North Fork Section of the Ozark Trail in southern Missouri (Howell Co.), I made sure to check the abundant flowering dogwood (Cornus florida) blossoms that were in gorgeous peak bloom at the time (early May). I’ve learned to check flowers of dogwood whenever I can, as they are quite attractive to a variety of insects but especially those groups of longhorned beetles (family Cerambycidae) that tend to frequent flowers as adults. In the case of flowering dogwood, most of the cerambycids that I encounter belong to two genera: Molorchus and Euderces. Both of these genera are known for their great resemblance to small ants, no doubt representing examples of Batesian mimicry (where a harmless species adopts the appearance or warning signals of a harmful species to gain protection from predators).

Tilloclytus geminatus

Tilloclytus geminatus on Cornus florida | North Fork Section, Ozark Trail, Howell Co., Missouri

During this particular hike I was determined to photograph Molorchus bimaculatus, common in Missouri during early spring on a great variety of flowering trees. On this day, however, the tiny (<10 mm length) beetles were rather scarce, and I had been frustrated in my attempts to get good photographs of the few that I had found. I’ve seen enough of these beetles over the years that I can recognize them quickly for what they are without the need to closely examine every “ant” that I see. So when I saw an “ant” that was too big and convex in profile to be Molorchus I almost discounted it as a true ant. Something about it, however, gave me pause, and when I looked closer I saw that it was, indeed, a longhorned beetle. But, it was not Molorchus, nor was it Euderces. Instead, it was the species Tilloclytus geminatus—an exciting find!

Tilloclytus geminatus

Adults in profile greatly resemble ants of the same size.

Tilloclytus geminatus has been recorded only sporadically from across the eastern U.S., where it has been reared from a variety of deciduous hardwoods (Craighead 1923, Rice et al. 1985). Perry (1975) did report rearing this species from Pinus virginiana (along with several other species normally associated with hardwoods); however, that record likely represents an ‘‘overflow’’ host (Hespenheide 1969) that is not typical of the species’ normal host preferences. I myself had never seen the species until the years after I published my checklist of Missouri cerambycids (MacRae 1994), having succeeded in rearing adults from a variety of previously unrecorded hardwood hosts that I collected at several localities across southern Missouri (MacRae & Rice 2007). It remains, for me, an infrequently encountered species—perhaps part of this a result of being overlooked due to its effective ant mimicry.

Tilloclytus geminatus

The anterior, oblique markings give the illusion of a constricted “waist”, while the posterior, transverse markings resemble the “sheen” of a shiny abdomen.

Unlike Molorchus and Euderces, this species has not been frequently associated with flowers as adults. In fact, the only report I am aware of is that of Rice et al. (1985), who reported adults on flowers of hawthorn (Crataegus sp.). Perhaps this additional find on Cornus is indicative of a true adult attraction to flowers by T. geminatus, although a single adult provides only weak support. However, a related ant-mimicking longhorned beetle—Cyrtophorus verrucosus—has been collected on flowers of roughleaf dogwood (Cornus drummondii) (MacRae 1994) as well as flowering dogwood (Scheifer 1998a). The floral attraction of ant-mimicking cerambycids may be more characteristic of species in the subfamily Cerambycinae, as only one flower record exists (Physocarpus opulifolius) for Psenocerus supernotatus (Wheeler & Hoebeke 1985) and none exist for Cyrtinus pygmaeus, both in the subfamily Lamiinae rather than Cerambycinae and the only other true ant-mimicking species in Missouri of which I am aware.

REFERENCES:

Craighead, F. C. 1923. North American cerambycid larvae. A classification and the biology of North American cerambycid larvae. Dominion of Canada, Department of Agriculture, Technical Bulletin No. 27 (new series), 239 pp. [Internet Archive].

Hespenheide, H. A. 1969. Larval feeding site of species of Agrilus (Coleoptera) using
a common host. Oikos 20:558–561 [JSTOR].

MacRae, T. C. 1994. Annotated checklist of the longhorned beetles (Coleoptera: Cerambycidae and Disteniidae) known to occur in Missouri. Insecta Mundi 7(4) (1993):223–252 [pdf].

MacRae, T. C. & M. E. Rice. 2007. Distributional and biological observations on North American Cerambycidae (Coleoptera). The Coleopterists Bulletin 61(2): 227–263 [pdf].

Perry, R. H. 1975. Notes on the long-horned beetles of Virginia, part III (Coleoptera: Cerambycidae). The Coleopterists Bulletin 29(1):59 [JSTOR].

Rice, M. E., R. H. Turnbow Jr. & F. T. Hovore. 1985. Biological and distributional observations on Cerambycidae from the southwestern United States (Coleoptera). The Coleopterists Bulletin 39(1):18–24 [pdf].

Schiefer, T. L. 1998a. A preliminary list of the Cerambycidae and Disteniidae (Coleoptera) of Mississippi. Transactions of the American Entomological Society 124(2):113–131 [JSTOR].

Wheeler, A. G., Jr. & E. R. Hoebeke. 1985. The insect fauna of ninebark, Physocarpus opulifolius (Rosaceae). Proceedings of the Entomological Society of Washington 87(2):356–370 [BioStor].

© Ted C. MacRae 2015

Missouri’s largest planthopper

Although I have long dedicated myself to beetles, I must confess that my first love was the so-called “Homoptera”—that now defunct order containing some really cool bugs (cicadas and hoppers—i.e., leafhoppers, treehoppers, planthoppers, froghoppers, armadillohoppers, etc.) and some not-so-cool bugs (aphids, whiteflies, mealybugs, and their kin)¹. Perhaps you already sense that it was only the cicadas and hoppers that I really liked, the other mentioned groups being… well… boring from my perspective as a collector (overwhelming numbers of tiny, soft-bodied, sessile insects that required preservation in alcohol or on slides²). Even within the “cool” homopterans, however, some groups interested me more than others. Leafhoppers were okay, but my interest in them derived mostly from the fact that they were the subject of my thesis work. Treehoppers, on the other hand, were my favorite because they were just so adorably bizarre, and cicadas also fascinated me due to their size and behavioral charisma.

¹The homopterans have since been subsumed within the larger order Hemiptera (true bugs)—an irritating but necessary consequence of molecular studies that have shown rather conclusively that hoppers and cicadas are more closely related to the other true bugs than they are to the group containing aphids, whiteflies and mealybugs.

²So, not only are they boring to curate, but they directly caused the first order of insects in which I became interested to be completely dismantled!

Poblicia fuliginosa on Silphium terebinthinaceum (prairie dock)| Barry Co., Missouri.

Poblicia fuliginosa on Silphium terebinthinaceum | Barry Co., Missouri.

The planthoppers also interested me, although many of the various families contained within the group seemed not much different to me than leafhoppers. One family, however, stood out—the Fulgoridae. Much larger than the other planthoppers, they seemed like a cross between a planthopper and a small cicada (okay, a very small cicada)—combining the hopping capabilities of the former with the size (almost) of the latter. I only rarely encountered these bugs in Missouri; actually it was only a single species that I ever found—Poblicia fuliginosa, one of only two species in the family known to occur as far north as Missouri (Bartlett 2014). Moreover, when I did find them, they were extraordinarily wary and difficult to approach and collect. Vernon Brou, in a comment at this species’ BugGuide page, describes their capture-avoidance capabilities perfectly:

These are nearly impossible to capture by hand netting, they are rocket propelled. A most [frustratingexercise in futility.—Vernon Antoine Brou, Jr., pers. comm. to Mike Quinn, 2012.

The abdomen is brightly colored red (barely visible in this photo).

The abdomen is brightly colored red (barely visible in this photo).

This past fall, while on a collecting trip in the White River Hills of extreme southwestern Missouri, I chanced upon a few individuals perching on the stems of prairie dock (Silphium terebinthinaceum) in a dolomite glade. Remembering how wary they were in my previous encounters, I figured I had little chance of successfully photographing any of them. I love a challenge, however, and with the help of field mate Stephen Penn I managed to get the shots shown here. Getting within the range of focus generally caused the insects to dart around to the backside of the stem. I took advantage of this behavior by getting myself set and focusing the camera on the bug (even though it was behind the stem) and then having Stephen move his insect net slowly toward the bug from the side to get it to dart back around the stem away from the net… right into my field of view! The first individual we tried to photograph took off rather quickly (rocket-propelled!), but fortunately we found another individual in the same clump of stems and succeeded in getting some shots.

In the second photo the bright red abdomen is barely visible on the underside of the insect. The entire abdomen is, in fact, bright red in obvious contrast to the otherwise dark and somber coloration of the insect. I’ve searched the literature but can find no mention of the function of the red abdomen, but I presume it serves a flash coloration function similar to the bright green abdomen of some jewel beetles to confuse potential predators by its visibility in flight and then sudden disappearance when the insect lands and folds its wings over the abdomen. I suppose an aposematic function is also possible given the red coloration, but I’m not aware that any hoppers are known to be chemically protected, and the fact that the red abdomen is seen only during flight also suggests a non-chemically based function.

REFERENCES:

Bartlett, C. R. 2014 (and updates). Planthoppers of North America. Available at: http://canr.udel.edu/planthoppers (accessed 12 November 2014).

© Ted C. MacRae 2014

Orange and black on gold

Trigonopeltastes delta on goldenrod (Solidago sp.) flowers | Stoddard Co., Missouri

Trigonopeltastes delta on goldenrod (Solidago sp.) flowers | Stoddard Co., Missouri

The spectacular amorpha borer, Megacyllene decora, was not the only black-and-gold colored beetle that I saw on the flowers of goldenrod (Solidago sp.) a few weeks ago. In addition were several delta flower scarabs, Trigonopeltastes delta. This species is much more commonly encountered than the amorpha borer—not only geographically but also throughout the season on a greater diversity of flowers. Nevertheless, I had failed in my previous attempt to photograph the species at the very same locality just a few weeks earlier due to the much higher summer temperatures and resultant flightiness of the beetles.

Trigonopeltastes delta
In the case of this beetle, the scientific name almost completely describes the beetle—the genus name being derived from the Greek words trigon (i.e., triangle, triangular) and pelt, (i.e., a shield), referring to the triangular and shield-shaped pronotum, and the species name based on the Greek letter Δ (“Delta”) in reference to the distinctive white triangle on the pronotum that resembles it. I mentioned the diversity of flowers on which adults of this beetle can be found. Pascarella et al, (2001) found this species on 13 different plant species (including mass aggregations numbering in the thousands on inflorescences of Sabal palm, Sabal palmetto) in their study of flower-visiting insects in the Everglades National Park. In Missouri, I see these beetles most commonly on Queen Anne’s lace (Daucus carota) and several other plants with white inflorescences such as American feverfew (Parthenium integrifolium), New Jersey tea (Ceanothus americanus), wild hydrangea (Hydrangea arborescens), and—most recently—hairy mallow (Hibiscus lasiocarpos). Interestingly, on this day there was an abundance of white-flowered snakeroot (Eupatorium sp.) in bloom at the same site, but I only saw the beetles on the yellow-flowered goldenrod.

Trigonopeltastes delta
It has been suggested that the Delta pattern on the pronotum and orange-and-black coloration of the elytra combine to mimic the appearance of paper wasps in the genus Polistes. Paper wasps are frequent visitors to many of the same flowers that these beetles frequent; however, the much smaller size of the beetles might suggest mimicry of aculeate hymenopterans (stinging wasps and bees) in general rather than paper wasps specifically. A more unusual type of mimicry has also been suggested in that a rear view of the beetle with its large, white, triangular pygidium seems to resemble the head of a hornet. Supporting this idea is the habit of the beetles to raise and hold their long hind legs in the air when disturbed in a manner that makes them resemble a hornet’s antennae!

Defensive posture with hind legs raised above abdomen.

Defensive posture with hind legs raised above abdomen (iPhone photo).

REFERENCE:

Pascarella, J. B., Waddington, K. D. & P. R. Neal. 2001. Non-apoid flower-visiting fauna of Everglades National Park, Florida. Biodiversity and Conservation 10(4):551–566 [abstract & pdf link].

© Ted C. MacRae 2014

Amorpha borer on goldenrod

Megacyllene decora (amorpha borer) | Stoddard Co., Missouri

Megacyllene decora (amorpha borer) | Stoddard Co., Missouri

One of my favorite longhorned beetle species is the amorpha borer, Megacyllene decora. Like its close relative, the locust borer—M. robiniae, this large, beautiful, black and yellow beetle is a classic harbinger of fall by virtue of its late-season adult activity period and affinity to flowers of goldenrod (Solidago) and snakeroot (Eupatorium). Compared to the locust borer, however, it is larger, chunkier, and more boldly marked, and despite the commonness of goldenrod flowers it is far less commonly encountered than the locust borer due to the more restricted habitat preferences of the larval host plant (false indigo—Amorpha fruticosa).

Megacyllene decora
The beetle in these photos is one of two that I found in late September at a site in the lowlands of southeastern Missouri. I’ve not seen the beetle at this site before, but I knew it must occur here because of the stands of false indigo that I noted during an earlier visit to the site. Considering the large number of plants present, two beetles is much less than I would have expected to see (in fact, both beetles were found in a single patch of goldenrod). I have previously featured this species (see A classic fall ‘bycid) from a site about 50 miles east of this one. At that site also only a few beetles were seen despite an abundance of larval host plants (but the adults occurring on snakeroot flowers instead of goldenrod). Only twice have I seen this species in numbers that I would consider plentiful (both times in western Missouri).

Megacyllene decora
Amorpha borers and locust borers are part of a larger complex of black and yellow insects that visit goldenrod flowers in the fall. These include a variety of bees, wasps, and other beetles (e.g., the delta flower scarab, Trigonopeltastes delta—family Scarabaeidae), but perhaps the most abundant is the goldenrod soldier beetle, Chauliognathus pensylvanicus—family Cantharidae (also called the Pennsylvania leatherwing). One can presume that any or all of these species serve as models for the longhorned beetles—bees and wasps are obviously protected from most predators by their ability to sting, and the bodies of soldier beetles are chemically protected by cantharidin, a highly toxic terpenoid that causes blistering and irritation of mucous membranes at low doses and can be fatal at higher doses. As the mimics, amorpha borers and locust borers could be expected to be less abundant than the models. However, considering how difficult-to-see these beetles can be when sitting on goldenrod flowers, their black-and-yellow coloration seems as though it could just as easily serve a cryptic function. It is even possible that mimicry and crypsis both have contributed to evolution of these beetle’s coloration.

Ted C. MacRae 2014

A truly disturbed garden spider

Argiope trifasciata vibrating web in response to disturbance.

Argiope trifasciata shaking its web in response to being approached.

This past weekend I made a trip to the White River Hills region in extreme southwestern Missouri. My goal was to find additional localities of the prairie tiger beetle (Cicindelidia obsoleta vulturina), which inhabits dolomite glades in the area and is disjunct from the main distribution in Texas and Oklahoma. As I was checking a particularly large glade complex in Roaring River State Park, I came upon this banded garden spider (Argiope trifasciata) that had spun its web across the span of branches from a gum bumelia tree (Sideroxylon lanuginosum). As I approached the spider the web began moving back and forth quite vigorously, and it occurred to me that there was not nearly enough wind for the web to be shaking to such degree. I stood still, and eventually the shaking stopped and the web became still again. To test whether it was really the spider shaking the web intentionally, I raised my net to one side and drew it closer to the spider, and once again the web began shaking back and forth just as vigorously as before. I watched the spider closely as the web shook, and I could see that the spider was actually flexing its two front pairs of legs back and forth to cause the shaking. It was clear at this point that the spider was doing this in response to my approach, probably as a defensive reaction to a perceived threat.

I suppose I have seen this behavior before but always assumed the web was just shaking in the breeze. Not until this time, with no wind to speak of and the web shaking quite rapidly, did it become clear to me that this was actually an intentional behavior exhibited by the spider. Eisner (2005) also notes this behavior, stating that Argiope spiders often engage…

…in a bobbing action, whereby through a quick flexion of its legs it sets the web into vibration, making itself a blurred target that is hard to grasp.

The photos used to make this animated gif were not easy to get. The spider was situated in a rather high and awkward-to-reach spot, and the iPhone had difficulty focusing on the spider while it was in motion. I overcame these problems by setting myself in a stable position, holding the iPhone in place, zooming the screen slightly (about 33%) and locking focus on the spider while it was still, and then asking my field buddy (Steve Penn) to approach the spider to trigger shaking. Once it began shaking it was a matter of holding down the shutter while keeping myself and the camera still long enough for a sufficient burst of photos (eight photos were used in this gif).

REFERENCE:

Eisner, T. 2005. For the Love of Insects. Harvard University Press, Cambridge, Massachusetts, 448 pp. [Google Books].

© Ted C. MacRae 2014