beetles

Graphisurus triangulifer in Missouri

/ Ted C. MacRae / 11 Comments

Graphisurus triangulifer | Sam A. Baker State Park, Missouri

Of the three species of the genus Graphisurus occurring in Missouri, G. triangulifer is both the most attractive and the least commonly encountered.  Back when I surveyed the Cerambycidae of Missouri (MacRae 1994), I examined only 45 specimens of this species in the major public and private collections of the state, compared to slightly more of the equally uncommon G. despectus and a whopping 271 of the übercommon G. fasciatus.  Nearly all of the specimens I examined of this species were encountered at lights, and it has been in this manner almost exclusively that I have seen the species for myself.

The species is named for the dark triangular markings on the elytra.

The individual in these photos was seen at Sam A. Baker State Park in the southeastern Ozark Highlands of Missouri during early July, and—like most of the others I have seen—it was attracted to my blacklight. I really don’t like photographing insects directly on the white landing sheet that I use for blacklighting, so I moved the beetle to the trunk of a nearby boxelder tree (Acer negundo) for a more natural looking background. There are a few reports of the species utilizing Acer for larval development (Lingafelter 2007), so this could be a very natural setting; however, I have not seen any actual records of the species being reared from that host. More often the species has been recorded breeding in dead sugarberry (Celtis laevigata). While I have conducted many rearings from Celtis, I’ve not yet succeeded in rearing this species—I suspect it probably breeds in larger diameter branches given its relatively large size (12–17 mm in length).  This idea is bolstered by the fact that the one adult that I did not encounter at lights was found on the trunk of a large, dead sugarberry near San Antonio, Texas.  Hoffman et al. (2002) noted that the species exhibits a southern, lowland distribution extending from Long Island to central Georgia, thence west to Texas and northward in the interior as far north as Ohio and Indiana (it has also been recorded from Kansas and, of course, Missouri).  This distribution pattern agrees largely with that of Celtis laevigata in the eastern U.S., suggesting that this plant may indeed be its primary host.  A fairly restricted host range for G. triangulifer would not be unexpected, since each of the other two species in the genus also exhibits a fair degree of host fidelity—G. despectus breeds almost exclusively in hickory (Carya spp.), while G. fasciatus breeds primarily in oak (Quercus spp.).

REFERENCES:

Hoffman, R. L., S. M. Roble, and W. E. Steiner, Jr. 2002. Thirteen additions to the known beetle fauna of Virginia (Coleoptera: Scirtidae, Bothrideridae, Cleridae, Tenebrionidae, Melyridae, Callirhipidae, Cerambycidae, Chrysomelidae). Banisteria 20:53–61.

Lingafelter, S. W. 2007. Illustrated Key to the Longhorned Woodboring Beetles of the Eastern United States. Coleopterists Society Miscellaneous Publications, Special Publication No. 3, 206 pp.

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.

Copyright © Ted C. MacRae 2011

Elytrimitatrix at my window

/ Ted C. MacRae / 7 Comments


This evening as I was sitting in my comfy chair, I noticed Stitch (one of the cats) pawing at the window. We live in the woods, so it is common for insects to land on the outsides of the windows after dark, attracted to the lights from within our home. Stitch was especially interested in a rather large beetle crawling frantically on the window, which I recognized quickly as the cerambycid beetle, Orthosoma brunneum. This big brown beetle is a member of the root-boring subfamily Prioninae, and although it is perhaps one of the commonest longhorned beetles in our area during July and August, I’ve not yet photographed it. As I debated whether to do so, I noticed the distinctive silhouette of another cerambycid beetle sitting quietly lower down on the window—smaller than O. brunneum but still decent-sized. I opened the window a crack (to keep all the other insects from rushing in), reached my hand through the crack, grabbed the beetle and in pulled it inside. It was a fine specimen of what is now known as Elytrimitatrix undata. I forgot all about the Orthosoma beetle and decided to photograph Elytrimitatrix instead.

While a member of the longhorned beetle family Cerambycidae, the group to which this species belongs (subfamily Disteniinae) has long been treated as sort of the “red-headed stepchild” of the family due to disagreement about its affinities to other cerambycid groups. It has at times been considered a tribe of the subfamily Lepturinae, a tribe of the subfamily Cerambycinae, a subfamily of its own, and even a separate family. Much of this disagreement focuses on details of its morphology despite the great superficial resemblance of the adults to other cerambycids. For now, it seems most workers are satisfied to regard the group as a distinct subfamily within the Cerambycidae, even though its exact relationships to other subfamilies still remain unclear.

Despite numerous representatives in the Neotropics, E. undata is the only member of the subfamily in the U.S., occurring broadly across the eastern and central states. For many years it was known as “Distenia” undata but was recently split out of that genus by Santos-Silva & Hovore (2007). Larvae have been recorded breeding in the dead wood of a variety of hardwoods as well as pine (the ultimate generalist), and adults are regular visitors at lights during the warm, muggy months of summer. I have also taken the species in numbers in traps baited with fermenting liquid (1 part molasses, 1 part beer, 8 parts water, and a packet of dry yeast) (MacRae 1994).

REFERENCE:

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.

Santos-Silva, A. & F.T. Hovore. 2007. Divisão do gênero Distenia Lepeletier & Audinet-Serville, notas sobre a venação alar em Disteniini, homonímias, sinonímia e redescrições (Coleoptera, Cerambycidae, Disteniinae). Papéis Avulsos de Zoologia 47:1–29.

Lined Jewel Beetle

/ Ted C. MacRae / 3 Comments

Buprestis lineata mating pair on lower trunk of Pinus echinata | vic. Calico Rock, Arkansas

Here is another of the several wood-boring beetle species that I encountered during my June trips to the sandstone glade complex near Calico Rock in north-central Arkansas.  Shortleaf pines (Pinus echinata), the only native pine in this region, are common on and around the glades due to their acidic soils, and this mating pair of Buprestis lineata (family Buprestidae) was found near the base of the trunk of one of the larger trees.  These were actually the first of a number of different wood-boring beetles that I found on this particular tree, others being Xylotrechus sagittatus, Chalcophora virginiensis, and the sumptuously beautiful Acanthocinus nodosus.  All of these species are classic pine-associates in the southeastern U.S.  After photographing this couple, I observed numerous other individuals flying to the tree, landing on its trunk and searching nervously for mates, then fleeing if I approached too close (except the unfortunate early few that I conscripted as ‘vouchers’).  The tree was a veritable singles bar for wood-boring beetles!

Despite their abundance in the area, the pines do not grow well on the glades due to the thinness of the soils (that is, where there is soil!).  Not only do the trees grow slowly, but they suffer reduced longevity and high turnover, producing an abundance of stressed and dying trees that wood-boring beetles in the families Buprestidae and Cerambycidae are only too happy to utilize.  Most species in these families (with notable exceptions such as the emerald ash borer, Agrilus planipennis) prefer dead or dying trees for larval development, largely because healthy trees are quite capable of fending off attacks by bleeding and overwhelming newly hatched larvae as they attempt to bore into the tree.  Adults are able to detect these stressed trees through chemoreception of host plant volatiles, thus, the presence of numerous wood boring beetle adults on an otherwise healthy-looking tree is a clue that the tree’s days are numbered.  I don’t know what it was about the tree that caught my attention and made me go over to take a look at it—perhaps just its large size, but it proved to be a fruitful detour.

Copyright © Ted C. MacRae 2011

More on ‘Conspicuous Crypsis’

/ Ted C. MacRae / 16 Comments

Acanthocinus nodosus on trunk of Pinus echinata | vic. Calico Rock, Arkansas

In my previous post (), I used the term ‘conspicuous crypsis’ to describe the sumptuously beautiful lichen grasshopper, Trimerotropis saxatilis, as an example of an insect that, despite strikingly conspicuous colors/patterns, blends in perfectly with its native surroundings. I don’t think this is a formally recognized ecological concept (and a quick search of the web and my limited ecology literature didn’t turn up anything about it) with any real biological/ecological relevance, but rather just a little irony that personally I find interesting.

The same individual in the above photograph in its original resting spot.

The photographs in this post were also taken during one of my June trips to the sandstone glade complex around Calico Rock, Arkansas and show another insect that I would describe as conspicuously cryptic. This is Acanthocinus nodosus, in my opinion one of eastern North America’s most attractive longhorned beetles (family Cerambycidae). This species occurs across the eastern U.S. (just sneaking up into southern Missouri), where the larvae mine the phloem beneath the bark of dead and dying pines (Linsley and Chemsak 1995). BugGuide describes it as “subtle, yet beautiful” with an antennal span in males reaching a spectacular 120 mm (that’s 5 inches, folks!). Perhaps others have encountered this beetle more commonly further south, but I have previously seen only single individuals on just three occasions—twice in the Ozark Highlands of southern Missouri (one at lights and another searching the trunk of a standing, decadent pine tree at night) and another at lights in Alabama. As a result, I was quite excited to find this individual clinging during the day to the trunk of a large shortleaf pine (Pinus echinata). The tree appeared healthy, but I found adults of several other wood boring beetles crawling on its trunk as well, suggesting that maybe the tree was stressed or in the initial stages of decline.

Subtle, yet beautiful!

I must confess that the first photograph above was staged—I had moved the beetle from its original resting spot and placed it on a part of the trunk where the bark color contrasted more strongly with the beetle to increase its visibility.  The second and third photos above and left show the beetle in its original resting spot and illustrate just how cryptic the beetle is when resting on older, more weathered pine bark.  Admittedly, the somber coloration of this species is not as extraordinary as the lichen-green of the lichen grasshopper, but I nevertheless find the slate gray with velvet black markings quite beautiful.  When mounted on pins and lined up neatly in a cabinet, individuals of this species are as attractive as any dead insect can be.  It was not until I saw this individual in Arkansas—and tried to photograph it during the day—that the cryptic function of its coloration and patterning became truly apparent to me.  Most species in the tribe Acanthocini (to which this species belongs) also exhibit somber coloration with variable black markings or mottling, although only a handful can be considered as ‘conspicuously cryptic’ as this one.

REFERENCE:

Linsley, E. G. and J. A. Chemsak.  1995. The Cerambycidae of North America. Part VII, No. 2: Taxonomy and classification of the subfamily Lamiinae, tribes Acanthocinini through Hemilophini. University of California Publications in Entomology 114:1–292.

Copyright © Ted C. MacRae 2011

Diminishing Stag Beetle

/ Ted C. MacRae / 14 Comments

This past June I made a couple of trips to north-central Arkansas. They were my first real efforts to collect insects in Arkansas, despite hundreds (literally) of trips to various localities throughout the Ozark Highlands in adjacent southern Missouri. The similarities between the two areas were obvious, yet there was also the feeling of a brand new area just waiting for exploration. On the second trip, I found a campground that looked good for blacklighting to see what wood-boring beetles I might be able to attract amongst the surrounding pine/oak-hickory forest. The evening was warm (very warm!) and humid with no moon—typically ideal for blacklighting, but beetles were sparse at the sheets for some reason (perhaps deterred by the obnoxiously unrelenting yells of drunk Arkansans and their out-of-control offspring?!). The evening, however, was not a total loss—at one point an enormous stag beetle landed on the top of the sheet.  It was so big that I couldn’t even fit it into the viewfinder of my camera:

I fiddled with the camera and changed some settings.  I got a little more of the beetle in the viewfinder this time, but it was still just too big:

Additional fiddling with the camera allowed even more of the beetle to be seen:

As I took the photographs, I even began wondering if the beetle itself was actually shrinking:

Eventually, it turned out to be a normal-sized beetle after all:

This is a female of the common eastern North American species Lucanus capreolus.¹  I don’t seem to encounter female stag beetles as often as the males, so this was still a nice find on an otherwise frustrating night.

¹ Two bonus point in the current BitB Challenge session to the first person who correctly explains how I know this.  Overall contenders: here’s your chance to score an advantage as we enter the final stretch in the current Challenge session.

Copyright © Ted C. MacRae 2011

Four-humped Longhorned Beetle

/ Ted C. MacRae / 8 Comments

Acanthoderes quadrigibba | Chalk Bluff Natural Area, Arkansas.

On a recent collecting trip, I went over to Chalk Bluffs Natural Area in the Mississippi Alluvial Plain of northeastern Arkansas.  My quarry was a population of Cylindera cursitans (ant-like tiger beetle) that has been reported from the site—one of the only known sites for the species in Arkansas.  While I was there, I noticed some movement on the trunk of a tree, and a closer look revealed that what appeared to be a piece of bark was actually a beetle—a longhorned beetle to be precise.  The elevated gibbosities of the pronotum and white, transverse fasciae of the elytra immediately identify it as Acanthoderes quadrigibba, a not uncommon species in the eastern U.S., but one that I still get excited about whenever I encounter it.

Note the four pronotal ''humps'' in this dorsolateral profile view.

Judging by the number and diversity of plant genera that have been recorded as larval hosts for this species—Linsley and Chemsak (1984) recorded Acer, Betula, Carya, Castanea, Celtis, Cercis, Fagus, Ficus, Quercus, Salix, Tilia, and Ulmus—you could be forgiven for thinking that this is one of the most common and abundant species of longhorned beetle in North America.  I have not found this to be the case, and I don’t think it is because I’m simply missing it due to its cryptic appearance.  Longhorned beetles in the tribe Acanthoderini are, like many species in the family, quite attracted to lights at night, and I’ve done plenty of lighting over the years.  What I have noticed is that nearly all of my encounters with this species have been in the Mississippi Alluvial Plain—an area rich with wet, bottomland forests that contrast markedly from the dry to dry-mesic upland forests that cover much of the southern two-thirds of Missouri.  I’ve also reared the species a few times from Salix, one of the host genera recorded by Linsley and Chemsak (1984).  In both cases, the wood was not freshly dead (as is commonly preferred by many other longhorned beetles), but a little past its prime and starting to get somewhat moist and punky.  In the case of this beetle, I suspect that the nature of the host wood may be more important than the species, the preference being for longer dead wood in moister environments.  Of course, observations by another collector in another state may completely obliterate my idea, but for now it sounds good.

A closeup photograph of the elytral markings of this beetle was the subject of ID Challenge #9, to which a record 18 participants responded (thanks to all who played!).  Troy Bartlett takes the win with 12 points (and attention to detail), while Dennis Haines, Max Barclay, Mr. Phidippus, and Josh Basham all score double-digit points.  Troy’s win moves him into the top spot in the overall standings of the current BitB Challenge Session with 23 pts, but Dave is breathing down his neck with a deficit of just a single point.  Tim Eisele and Max Barclay have also moved to within easy striking distance with 19 and 18 points, respectively, and several others could make a surprise move if the leaders falter.  I think I’ll have one more challenge in the current session before deciding the overall winner—look for it in the near future. 

REFERENCE:

Linsley, E. G. and J. A. Chemsak. 1984. The Cerambycidae of North America, Part VII, No. 1: Taxonomy and classification of the subfamily Lamiinae, tribes Parmenini through Acanthoderini. University of California Publications in Entomology 102:1–258.

Copyright © Ted C. MacRae 2011

Sugarcane Weevil in Brazil

/ Ted C. MacRae / 3 Comments

Sphenophorus levis (sugarcane weevil) | Conchal, Brazil.

Brazil is one of the world’s top producers of sugarcane, and they have the Middle East to thank for it.  While the U.S. was responding to the 1973 OPEC oil embargo by building bigger and bigger SUVs, Brazil aggressively developed an alternative fuels industry based on sugarcane for ethanol production.  Today, about half of Brazil’s sugarcane is milled for ethanol, yet despite this enough raw sugar is produced from the remaining sugarcane crop to rival India as the world’s top producer.

The large acreage devoted to sugarcane and tropical climate in which it is grown make Brazil’s crop especially vulnerable to infestation by insect pests—and there are many!  One of the most important is Sphenophorus levis (sugarcane weevil, or “bicudo da cana-de-açúcar”).  Larvae bore in the roots and crown of the plant, reducing biomass accumulation and longevity.  This feature of the insect’s biology also makes the larvae extraordinarily difficult to control, since they are largely protected from chemical applications by surrounding plant tissues.  This adult beetle was captured in a field trap placed in a sugarcane field in Conchal, approximately 175 km N of São Paulo.  The traps consist of split sugarcane stalks buried under debris within crop rows—adults are attracted to the cut surface of the stalks, where they congregate in numbers.  Traps are used not only to monitor beetle occurrence and abundance in fields, but also to provide a source of insects for laboratory rearing and evaluation of control test agents.

Copyright © Ted C. MacRae 2011

Tracking Tetraopes texanus with Terry

/ Ted C. MacRae / 12 Comments

Last month I traveled to Starkville, Mississippi to meet with an academic cooperator at Mississippi State University.  While arranging the trip, I contacted Terry Schiefer (no, not the fashion jewelry designer, but curator at the Mississippi Entomological Museum) to let him know I would be visiting.  Considering that late May should be pretty good insect collecting in that area, I wanted to see if he might be interested in doing a little beetle collecting after I finished up with my meetings.  Terry also specializes in Coleoptera and shares with me an interest in the taxonomy and faunistics of Cerambycidae and Cicindelinae.  I first met Terry some 13 years ago during my previous visit to MSU; I remember ogling at an impressive series of Aegomorphus morrisii, a spectacular species of longhorn beetle that was known at that time by precious few specimens and that he had recently found in Mississippi.  We hadn’t seen each other since but managed to keep in contact with occasional correspondence during the course of our longhorn studies.

Me & Terry Schiefer | Noxubee National Wildlife Refuge, May 2011.

Terry was more than happy to go beetle collecting with me, and among the possibilities that he mentioned when I arrived at the museum was nearby Noxubee National Wildlife Refuge.  I had done a little collecting there on my last visit, but I was especially intrigued when he mentioned the local population of an uncommon milkweed beetle species, Tetraopes texanus, that he had reported in one of the refuge’s prairie remnants (Schiefer 1998).  I have only seen this species once, up here in in east-central Missouri and which I reported as the species’ northernmost known population (MacRae 1994).  My more recent attempts to find this species have not been successful, so I was excited at the chance to see this longhorned species once again.

We arrived at the prairie with plenty of daylight to spare and began walking through the area where Asclepias viridis (its presumed host in Mississippi; in Missouri I found it on Asclepias viridiflora) was growing.  Typically milkweed beetles are quite approachable, having nothing to fear from predators by virtue of the cardiac glycosides that they sequester in their bodies from their milkweed foodplants and advertise so conspicuously with their bright red and black coloration.  Thus, we were looking for beetles sitting brazenly on the plants, but none were seen.  Eventually, Terry saw one in flight, and then I saw one in flight as well.  For some time, this was the only way we were seeing the beetles, and only by slowing down and scanning the prairie vegetation more carefully and deliberately did we begin to see the adults sitting on vegetation.  Interestingly, very few of them were seen actually sitting on milkweed plants.  Rather, they were on all manner of other plants, and they were very quick to take flight on our approach.  This was playing havoc with my desire to get field photographs of the beetles, especially field photographs on the host.  I decided that any photograph—host plant or not—was better than none, so I began attempting some shots.  My first one didn’t work out so well:


Finally I was able to get one of the beetle sitting on a plant, but the dorsal characters can’t be seen, nor is there anything about the photo that allows the species to be distinguished as T. texanus (the abruptly attenuate last antennomere distinguishes it from similar-appearing species):


Progress—more of the dorsal surface can be seen in the photo below, and the beetle is actually sitting on a milkweed plant.  However, the antennal tips are still frustratingly out of focus.  Note the completely divided upper and lower lobes of the eye—Tetraopes beetles give new meaning to the term “four-eyes”:


I chased beetle after beetle in flight, endlessly zigzagging across the prairie in what had to be a spectacle to any unknown observer.  Eventually, we found a beetle sitting on its host plant, and it remained calm during my deliberate approach.  I circled around for a good view of the dorsal surface and snapped off an apparent winner—everything in focus, good composition… but arghh, the antennal tips were clipped!


I kept at it and was about to back off a bit on the magnification and switch to landscape mode so I could get the full antennae in the frame when the beetle turned in a most fortuitous manner—nicely positioning its distinctive antennal tip right in front of a bright green leaf for contrast.  My friends, I present Tetraopes texanus on its presumed host plant, Asclepias viridis!


Terry and I were both puzzled by the flighty, nervous behavior that the beetles were exhibiting.  Neither of us had seen such behavior with milkweed beetles before, and I’m not sure I can offer any explanation for such.  I’d be interested in hearing any ideas you might have.

My thanks to Terry for showing me a few of his favorite spots (allowing me to collect a few choice species of longhorns), and to my co-worker/colleague Jeff Haines for indulging my desire mix a little beetle collecting into the business trip.  I hope they enjoyed it as much as I did.

REFERENCES:

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

Schiefer, T.L. 1998. Disjunct distribution of Cerambycidae (Coleoptera) in the black belt prairie and Jackson prairie in Mississippi and Alabama. The Coleopterists Bulletin 52(3):278–284.

Copyright © Ted C. MacRae 2011