scarabs

Party on a pin oak

/ Ted C. MacRae / 9 Comments

In September 2012 while collecting in western Oklahoma (Weatherford) I came across this interesting scene. It had been exceedingly dry in the area, and because of this few insects were out and about in the small city park that I stopped by to check for the presence of tiger beetles. I had nearly completed my circuit of the park when I came upon a moderate-sized pin oak (Quercus palustris) tree and noticed something on the lower trunk:

Six insect species representing five families in four orders share a sap flow.

Six insect species representing five families in four orders share a sap flow on the trunk of a pin oak.

No less than six insect species representing four orders were seen all huddled together at a darkly stained sap flow. This could be the result of slime flux, a bacterial disease that usually affects deciduous hardwoods that are under stress and results in darkly stained weeps on the trunk that are known to be attractive to a variety of insects. At the center sat a green June beetle (Cotinis nitida) and three bumble flower beetles (Euphoria inda)—all in the family Scarabaeidae (subfamily Cetoniinae). Covering the scarab beetles were half a dozen Texas Tawny Emperor (Asterocampa clyton texana) butterflies (family Nymphalidae, or Brushfooted Butterflies), and milling around the perimeter was a velvet ant (Dasymutilla creusa, I believe) in the family Mutillidae, an apparent flesh fly (family Sarcophagidae), and a true ant (family Formicidae). I guess this would be the equivalent to a watering hole in Africa with a lion, a hyena, a baboon, three vervet monkeys and six zebras all crouched shoulder-to-shoulder at its edge.

Euphoria sepulchralis feeds on a sap flow higher up on the trunk.

Euphoria sepulchralis feeds on a sap flow higher up on the trunk.

Further up on the trunk, yet another species of scarab beetle, a dark flower scarab (Euphoria sepulchralis) was found feeding on a smaller sap ooze. Unlike the diverse aggregation of insects on the lower ooze, this guy had managed to keep the ooze all to himself.

Cotinus nitidus | Weatherford, Oklahoma

Cotinis nitida | Weatherford, Oklahoma

Green June beetles, especially, are known for their feeding on sap oozes. The beetles are actually attracted to the odors caused by fermentation of the sap rather than the sap itself. It has been reported that the presence of alcohol in fermenting sap can affect the behaviour of insects that feed upon it, causing them to act “stupid and lethargic.” I did not see any such behavior, but I did notice that the insects were not at all skittish and loath to leave the sap.

Copyright © Ted C. MacRae 2013

Sunday scarab: Phileurus valgus

/ Ted C. MacRae / 7 Comments
Phileurus valgus (Linnaeus) | Otter Slough Conservation Area, Stoddard Co., Missouri

Phileurus valgus (Linnaeus) | Otter Slough Conservation Area, Stoddard Co., Missouri

Few beetles enjoy more popularity than the scarabs (family Scarabaeidae)¹, and within that group certainly the members of the subfamily Dynastinae are the most popular of all due to their often enormous size and presence of highly developed horns on the head and pronotum. The largest beetles in the U.S. (at least, by weight)—the Hercules beetles, genus Dynastes—belong to this subfamily, and in the tropical regions of the New World members of the genus Megasoma (literally meaning “giant body”) are among the heaviest-bodied beetles in the world (ironically, the title spot goes to members of the genus Goliathus in the subfamily Cetoniinae). Of course, almost without exception in the insect world exceptions apply, and not all dynastine scarabs are large, heavy-bodied beetles. In fact, members of the genus Cyclocephala are often mistaken for May beetles (subfamily Melolonthinae), while members of the genus represented by the species featured in this post—Phileurus—are sometimes mistaken for smallish “bess beetles” (Odontotaenius disjunctus) in the family Passalidae due to their flattened and parallel-sided body.

¹ Except maybe tiger beetles, jewel beetles, and longhorned beetles (wink!).

This species resembles and is sometimes mistaken for the common "bess bug."

This species resembles and is sometimes mistaken for the common “bess bug.”

Phileurus is a primarily Neotropical genus, with only two species ranging north into the United States and one, P. valgus, occurring broadly in the eastern United States. Despite its broad distribution, P. valgus seems to be more common in the southern part of the country and has been recorded under bark of decaying wood and attracted to lights. Saylor (1948) notes that Richter reared a specimen from a larvae collected in a cavity of a dead basswood (Tilia sp.) tree, and adults have also been reared from larvae collected in a blackjack oak (Quercus marilandica) snag (Taber & Fleenor 2005). The individual featured here was one of several that I found under the lower trunk bark of a large, standing, dead pin oak (Q. palustris) tree growing in a wet, bottomland forest in the Mississippi Alluvial Plain of extreme southeastern Missouri. I have seen this species from time to time over the years—never abundantly—but these are the first that I have seen in a situation other than being attracted to lights. The bark was quite loose and covered wood that was soft and well-decayed, and three adults were found embedded within a granular frass-filled gallery directly beneath the bark. One can presume that larvae could also have been found within the wood had I done a little digging.

The head of this species is adorned with three small cephalic tubercles.

The head of this species is adorned with three small cephalic and one pronotal tubercles.

Taber & Fleenor (2005) also note that adults of this species possess structures known to be used by other beetles for sound production, but they did not say whether they have heard this beetle making sounds. I have never heard sounds from these beetles when handling them, either. This contrasts with true bess beetles, which stridulate to make a “kissing” sound when handled.

REFERENCES:

Saylor, L. W. 1948. Synoptic revision of the United States scarab beetles of the subfamily Dynastinae, No. 4: Tribes Oryctini (part), Dynastini, and Phileurini. Journal of the Washington Academy of Sciences 38(5):176–183.

Taber, S. W. & S. B. Fleenor. 2005. Invertebrates of Central Texas Wetlands. Texas Tech University Press, Lubbock, 322 pp. [preview].

Copyright © Ted C. MacRae 2013

An interesting flightless May beetle

/ Ted C. MacRae / 6 Comments

I suppose you are an entomologist?

Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name. No man can be truly called an entomologist, sir; the subject is too vast for any single human intelligence to grasp.

Phyllophaga cribrosa | Gloss Mountain State Park, Major Co., Oklahoma

Phyllophaga cribrosa | Alabaster Cavern State Park, Woodward Co., Oklahoma

I suppose the above quote from The Poet at the Breakfast Table, by Oliver Wendell Holmes, Sr., applies just as well to those who would call themselves coleopterists, for restricting oneself to the study of beetles diminishes by scarcely more than half the known diversity of all insects. I still dare to call myself a coleopterist, but I’m the first to admit that while there are a few groups of beetles that I know very well, there are many more that I know only superficially and some that befuddle me completely. An example of the latter is May beetles (family Scarabaeidae, genus Phyllophaga). With more than 400 species in North America (Ratcliffe & Jameson 2010), it is one of the most speciose genera in our fauna. Not surprisingly, species identifications can be very difficult, oftentimes relying on examination of male and female genitalia.

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The flightless adults are most often found on the ground or low vegetation.

Not all species of Phyllophaga, however, are difficult to identify. The species shown here—P. cribrosa—is rather easily recognized within the genus by its oval, convex shape, shining black coloration, cribrose (perforated like a sieve) surface, 10-segmented antennae, and flightless nature. The resemblance to certain darkling beetles (family Tenebrionidae) is striking, although I suspect this may be a result of convergent adaptation to dry habitats rather than mimicry (Kaufman & Eaton 2007). While most species of Phyllophaga are nocturnal and capable of flight, adults of P. cribrosa are flightless and can be found crawling on the ground and clinging to low vegetation during the day. I found these beetles this past June at several locations in northwestern Oklahoma.

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The distinct elytral furrows distinguish P. cribrosa from closely related species.

There are at least two other closely related species in the genus (i.e., P. epigaea and P. zavalana) that resemble P. cribrosa; however, both of these species are restricted to Texas, and they lack the distinct longitudinal elytral furrows exhibited by P. cribrosa. The species is said to be an occasionally serious pest of crops (Luginbill & Painter 1953), although I suspect that in most cases this results from new plantings of crops in former grasslands because of the limited dispersal abilities of the beetles.

REFERENCES:

Eaton, E. R. & K. Kaufman. 2007. Kaufman Field Guide to Insects of North America. Houghton Mifflin Harcourt, 391 pp.

Luginbill, P., Sr. & H. R. Painter. 1953. May beetles of the United States and Canada. U.S. Department of Agriculture Technical Bulletin 1060, 102 pp,

Ratcliffe, B. C. & M. L. Jameson (eds.). 2010. Generic Guide to New World Scarab Beetles (available at: http://www-museum.unl.edu/research/entomology /Guide/index4.htm).

Copyright © Ted C. MacRae 2013

You know what bugs me about dung beetles?…

/ Ted C. MacRae / 12 Comments
...Their silly little shit-eating grins!

…Their silly little shit-eating grins!

Okay, I know this isn’t a true dung beetle, but this earth-boring scarab (family Geotrupidae) is close enough that I’ll take the opportunity to use one of my favorite dung beetle jokes.¹ This is one of several individuals that I saw on a late October hike along the North Fork Section of the Ozark Trail in extreme south-central Missouri (just a few miles north of the Arkansas border). I regard these beetles to represent the species Geotrupes splendidus based on the punctured elytral striae, sutural striae ending at the scutellum, bright green coloration, and obvious punctures in the lateral areas of the pronotum. Of the half dozen adults that I saw during the day, all were found singly on animal dung or on the ground nearby.  This was the most abundantly I’ve ever seen this species—up to that point I’d accumulated only a handful of specimens, always on mild days in late fall or early winter in association with animal dung on trails through high quality woodlands. The timing and circumstance is also true for Geotrupes blackburnii, the only other species in the genus that I have collected in Missouri—albeit much more commonly and abundantly than G. splendidus and easily distinguished from that species by its slightly smaller size, nearly impunctate pronotum and all black coloration.

¹ By the way, I don’t recall the provenance of that joke, other than I saw it as a one-frame cartoon, featuring two entomologists talking to each other, posted on a Department of Entomology door while I was in graduate school—way back in the early 1980s. If you know please tell me!

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Geotrupes splendidus miarophagus | Ozark Co., Missouri—yes, it’s sitting on shit!

An interesting contrast between this species and true dung beetles (scarabs in the subfamily Scarabaeinae and representing such genera as Copris, Phanaeus, Canthon, Onthophagus, etc.) is the fact that while this species can and does utilize dung for both larval development and adult feeding, it is not the preferred food. Rather, adults are more often found feeding on fungus, and leaf litter—tightly packed by the adult at the end of a burrow in the soil, is most often used for larval development (Howden 1055). This does not seem to be a universal feature of the genus, as the common Missouri species, G. blackburnii, does seem to prefer dung for larval development. This is not to say that either species is exclusive in its preference—both seem to be more flexible in food choice than the true dung beetles, but in reality the larval biology of a great many species in this and other genera of the family remain unknown.

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The opinion of scarab expert would be most helpful at this point. This species is broadly distributed across eastern North America, with eastern populations generally brighter green and western populations (e.g., here in Missouri) more often yellow-green with golden or reddish hints but ranging to dark purple. In fact, all but one of the Missouri specimens in my collection are dark purple, the other being green similar to the six beetles I saw on this date. Howden (1955) recognized the western forms as a separate subspecies, G. splendidus miarophagus (originally described as the species G. miarophagus by Thomas Say). These two subspecies are listed as valid in the recent checklist of Nearctic Scarabaeoidea (Smith 2003), and the specimens in my collection from Missouri are labeled as such by scarab expert Bill Warner. Despite this, most other sources I’ve checked—including BugGuide—list G. miarophagus as a synonym of G. splendidus. Color alone—especially when it is as variable as in this species—seems weak justification for subspecific distinction. Howden (1955) mentions a curious case of G. s. miarophagus utilizing fresh grass clippings for larval development; however, it is difficult to imagine this as anything more than just a very recent adaptation. If there are other reasons supporting subspecific distinction besides deference to Henry Howden, I’d be interested in knowing what they are.

REFERENCES:

Howden, H. F. 1955. Biology and taxonomy of North American beetles of the subfamily Geotrupinae with revisions of the genera Bolbocerosoma, Eucanthus, Geotrupes and Peltotrupes (Scarabaeidae). Proceedings of the United States National Museum 104:151–319.

Smith, A. B. T. 2003. Checklist of the Scarabaeoidea of the Nearctic Realm. Version 3. Electronically published, Lincoln, Nebraska. 74 pp.

Copyright © Ted C. MacRae 2013

It’s always a happy day…

/ Ted C. MacRae / 7 Comments

072_066_0400_cover…when the latest issue of The Coleopterists Bulletin arrives in my mailbox. On this occasion it was the December issue of Volume 66—nine papers and eight scientific notes filling 84 pages of beetle awesomeness. It’s pure elytral ecstasy! I presume I am like most subscribers—rapidly scanning the Table of Contents on the back cover to see if any deal directly with my preferred taxa. Yes! Two papers dealing with Buprestidae (jewel beetles), one on Cerambycidae (longhorned beetles), and one on Cicindelinae (tiger beetles)—a real bonanza. After that, a more cursory look through the rest of the Table of Contents to see what other papers look interesting enough to at least scan through.

For me the most interesting are the two Buprestidae papers, with Hansen et al. documenting new state records, larval hosts, and biological notes for 47 North American species and Westcott & Murray reporting the introduction into the U.S. of yet another Eurasian exotic (Trachys minutus) and its apparent establishment in Massachusetts. As the current “keeper” of distributional records and host plant associations for North American jewel beetles (along with Rick Westcott, Salem, Oregon), I will be busily updating my database over the next few days to reflect these new records. I am a great fan of “notes” papers such as these (and am, in fact, currently finishing a similar manuscript with co-author Joshua Basham, who is also a co-author on the Hansen et al. paper). However, I do have a few quibbles—Hansen et al. report Agrilus  quadriguttatatus as a new record for Tennessee, but it is already known from that state, and Cercis canadensis (eastern redbud) is reported as a new larval host for Anthaxia (Haplanthaxia) cyanella despite the prior records from that host by Knull (1920) and Hespenheide (1974). More puzzlingly, the authors record Agrilus lecontei celticola from locations in eastern Tennessee despite guidance from me on several occasions that this subspecies, while perhaps distinctive in Texas, transitions broadly across Louisiana and Mississippi  with the nominate subspecies. As such, material from eastern Tennessee cannot be regarded conclusively to represent this subspecies (and I remain unconvinced even that the subspecific distinction is warranted). Lastly, in recording Actenodes simi from Tennessee, the authors mention that the closest previous record is from Missouri with no specific locality mentioned (Fisher 1942), even though I recently recorded several specific locations for the species in eastern and southern Missouri (MacRae & Nelson 2003). The overall impression is that the authors are not fully versed in recent literature on Buprestidae and have instead relied exclusively on the recent Nelson et al. (2008) catalogue—known amongst buprestid workers to be incomplete and with errors—as the only source for determining the status of their records.

Among Cerambycidae, Raje et al. report the results of molecular analyses on two color forms of Sternidius alpha. This broadly distributed and highly variable species exhibits multiple color variants across its range, leading to the description of multiple subspecies that were eventually synonymized under the current name. Their analysis of the barcoding region of the cytochrome oxidase I gene, however, revealed three distinct clades among the two color forms, suggesting the potential for taxonomic significance. More work, of course, is needed from additional color morphs from different localities.

Finally, my friend Matt Brust and colleagues discuss the ovipositional behavior of numerous species of North American tiger beetles, unexpectedly finding that many oviposit only after digging some distance below the surface of the soil. This information is extremely valuable for those interested in rearing tiger beetles for description of larval stages, expanding the window of survey for species with limited temporal occurrence, and cross-breeding studies. To that end, and of greatest interest to me, they have included numerous observations from their own studies that have resulted in the development of successful protocols and rapid rearing of large numbers of larvae to adulthood.

cso 66-4Mco14.qxdActually, there is one more thing… For several years now the December issue, as a bonus, has been accompanied by the Patricia Vaurie Series Monograph as a supplement to that year’s volume. This year’s issue features a revision of the scarab genus Euphoria by Jesús Orozco, and although I have not studied it carefully it looks like a robust treatment of the group. Yes, I know that scarabs are not one of my primary interest groups, but show me a coleopterist that—regardless of the group they work on— does not stop and collect these gorgeous, colorful, flower-loving beetles whenever they encounter them and I’ll show you a coleopterist that is far too restrictive in their natural history interests! Based on examination of nearly 19,000 specimens from 67 collections, the work considers 59 valid species (ten of which are described as new) distributed throughout the Western Hemisphere. Complete with keys to species and, for each, synonymy, description, diagnosis, taxonomic history, natural history, temporal occurrence geographic distribution, and—of critical importance in my opinion—full data for all specimens examined, it is everything a good revision should be. Then there are the color plates—one full page for each species—with a large dorsal habitus view, closeups of the head, male genitalia, and color variants, a temporal distribution chart, and a map of its geographical distribution. Again, while I may not be a serious student of scarabs, you can bet that I’ll be going back through my holdings of Euphoria beetles and checking them to make sure they conform to this new standard of knowledge on the group.

REFERENCES:

Brust, M. L., C. B. Knisley, S. M. Spomer & K. Miwa. 2012. Observations of oviposition behavior among North American tiger beetle (Coleoptera: Carabidae: Cicindelinae) species and notes on mass rearing. The Coleopterists Bulletin 66(4):309–314.

Fisher, W. S. 1942. A revision of North American species of buprestid beetles belonging to the tribe Chrysobothrini. U. S. Department of Agriculture, Miscellaneous Publication 470, 1–275.

Hansen, J. A., J. P. Basham, J. B. Oliver, N. N. Youseef, W. E. Klingeman, J. K. Moulton & D. C. Fare. 2012. New state and host plant records for metallic woodboring beetles (Coleoptera: Buprestidae) in Tennessee, U.S.A. The Coleopterists Bulletin 66(4):337–343.

Hespenheide, H. A. 1974.  Notes on the ecology, distribution, and taxonomy of certain Buprestidae.  The Coleopterists Bulletin 27(4) [1973]:183–186.

Knull, J. N. 1920. Notes on Buprestidae with description of a new species (Coleop.). Entomological News 31(1):4–12.

MacRae, T. C. and G. H. Nelson. 2003. Distributional and biological notes on Buprestidae (Coleoptera) in North and Central America and the West Indies, with validation of one species. The Coleopterists Bulletin 57(1):57–70.

Nelson, G. H., G. C. Walters, Jr., R. D. Haines, & C. L. Bellamy.  2008.  A Catalogue and Bibliography of the Buprestoidea of America North of Mexico.  Coleopterists Society Special Publication No. 4, The Coleopterists Society, North Potomac, Maryland, 274 pp.

Orozco, J. 2012. Monographic revision of the American genus Euphoria Burmeister, 1842 (Coleoptera: Scarabaeidae: Cetoniinae). Coleopterists Society Monographs, Patricia Vaurie Series No. 11, 182 pp.

Raje, K. R., V. R. Ferris & J. D. Holland. 2012. Two color variants of Sternidius alpha (Say) (Coleoptera: Cerambycidae) show dissimilar cytochrome oxidase I genes. The Coleopterists Bulletin 66(4):333–336.

Westcott, R. L. & T. C. Murray. 2012. An exotic leafminer, Trachys minutus (L.) (Coleoptera: Buprestidae), found in Massachusetts, U.S.A. The Coleopterists Bulletin 66(4):360–361.

Copyright © Ted C. MacRae 2013

Bichos Argentinos #3 – “Bicho Torito”

/ Ted C. MacRae / 16 Comments

Diloboderus abderus, male | Buenos Aires, Argentina

In her appeal for submissions for her upcoming issue of An Inordinate Fondness, Susannah lamented the paucity of beetles in the closing weeks of her northern winter and mentioned in passing that even I had gone more than a week without posting about this great order.  I hadn’t realized that myself, so here I present Diloboderus abderus, one of the beetles that I encountered during my visit last weekend to La Reserva Ecológica Costanera Sur in Buenos Aires, Argentina.  This species, known commonly in Argentina as bicho torito (“little bull bug”) is common enough in Argentina and southern Brazil, where its white grub larvae have become somewhat of a pest in lawns, pastures, and grass crops such as wheat by way of feeding on the roots.  I first encountered this species during one of my previous trips to Argentina, where during a rain storm I saw literally hundreds of adults emerging from mowed grass medians in the city streets of Pergamino.  These photographs show two of numerous dead individuals that I found laying on the ground of similar medians just outside the reserve.  As with many scarab beetles in the subfamily Dynastinae (containing also the recently featured Dynastes tityus), males (above) are armed with pronotal and cephalic horns – presumably for use in sexual combat – while females (below) are unarmed.

Diloboderus abderus, female | Buenos Aires, Argentina

Copyright © Ted C. MacRae 2011

North America’s largest scarab beetle

/ Ted C. MacRae / 28 Comments

Dynastes tityus male - USA: Missouri, Jefferson Co., DeSoto

As one of North America’s largest, most written about, and most photographed beetles, Dynastes tityus (eastern Hercules beetle) hardly needs an introduction.  I photographed this male specimen from my collection back in December while testing my DIY diffuser for the MT-24EX twin flash and 100mm macro lens.  It’s a good test subject for such – its glossy exoskeleton may be beauty to the eye but is the bane of flash photographers, and its nearly 60mm of length demand a huge subject-to-lens distance that gives even the largest lens-mounted flash a small apparent size.  Nevertheless, the diffuser did a pretty good job of creating even illumination and preventing harsh specular highlights, giving almost the effect of an indirect strobe in a white box.

Dense setae adorn the underside of the thoracic horn of the male.

I hadn’t really noticed until I took the photos the dense adornment of setae (hairs) on the underside of the thoracic horn.  While setae in insects most often perform a tactile function, the density and placement on the horns of the males of these beetles makes me wonder if they might serve more of a display function.

Despite the overwhelming popularity of this beetle amongst hobbyist breeders and its widespread occurrence across the eastern United States (and the internet), it is not one that I have encountered with much frequency myself.  I suspect this is due to the position of Missouri near its western limit of distribution – likely a function of the species’ preference for moist treehole cavities with rotting wood in which the larvae can develop.  This particular specimen was given to me many years ago by a nursery grower in Jefferson Co. during my first job out of graduate school – before I’d ever found one myself, but since then I’ve encountered perhaps half a dozen or so at blacklights in mesic forests across the eastern Ozark Highlands.  Most recently (last summer) I found a female sitting on my driveway, apparently attracted to the mercury vapor lamp above the garage that I leave on occasionally during the months of June and July just for such purpose.

Copyright © Ted C. MacRae 2011

Frenatae 2011 Calendar

/ Ted C. MacRae / 13 Comments

Ralph Holzenthal - Tabanidae. Adobe Illustrator, gradient mesh/Adobe Photoshop.

Even though we’re now in the latter part of February, I wanted to spread the word about a cool insect-themed calendar shown to me by a colleague during my recent trip to Brazil. Produced by Frenatae, the Graduate Student Entomology Club at the University of Minnesota, the calendar features original work by students using computer illustration techniques taught in a UMN course titled, ENT 5051, Scientific Illustration of Insects. The mastermind behind this course is Dr. Ralph W. Holzenthal, who – as can be seen by the stunning image above of a female (L) and male (R) Tabanus lineola – knows a thing or two about insect illustration! While the course covers traditional techniques such as pen & ink, pencil, watercolor, etc., its major emphasis is on computer-assisted techniques using Adobe Illustrator® and Photoshop®. This includes instruction on preparing full habitus color illustrations of insects on the computer. How I wish a course such as this had been available when I was in graduate school (of course, how I wish computers had been available when I was in graduate school!).

While Dr. Holzenthal’s illustrative skills are obvious, it’s also clear that he excels at teaching these skills to his students, as evidenced by this selection of my favorite images (not surprisingly, all beetles!) from the course website galleries:

Caitlin Krueger - Scarabaeidae

Martha Megarry - Scarabaeidae

Heather Cummins - Zopheridae

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It should be pointed out that all of these Photoshop illustrations represent original artwork and not modified photographs!

I ordered my copy of the calendar as soon as I returned home from my trip. You can order one too by sending a check for $12 to the following address:

Frenatae
1980 Folwell Ave Rm 219
St Paul, MN 55108

My thanks to Dr. Holzenthal for allowing me to post this small selection of images from his website.

Copyright © Ted C. MacRae 2011