insects

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

Bichos Argentinos #2 – Pseudomyrmex sp.

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Pseudomyrmex sp. (twig ant) | Reserva Ecológica Costanera Sur, Buenos Aires, Argentina

One of the insects I tracked at La Reserva Ecológica Costanera Sur in Buenos Aires, Argentina last weekend was this twig ant in the genus Pseudomyrmex.  I had noticed these slender, wasp-like ants previously on trips to the U.S. desert southwest, but it wasn’t until I read a couple of recent posts about them at Myrmecos and 6legs2many that I knew specifically what they were. 

Alex characterizes these ants as “delightfully gentle, quirky little insects.”  What he didn’t mention is how frenetic and unceasing they are as they forage amongst the shrubbery.  I must have taken a couple dozen shots of several individuals over the course of the day, deleting every single one on the spot because I couldn’t get a clear, close, focused, nicely composed, unobstructed image.  Their habit of crawling rapidly along slender twigs is problematic enough, with little opportunity to brace the camera against anything steady and spend time composing the shot.  Add to that the frequently thorny nature of the trees they were roaming and their annoying habit of darting around to the backside of whatever twig they were on whilst trying to follow them in the viewfinder, and I almost decided I’d met my match and could do without the shot.  In the latter part of the day I encountered this individual, and as I already had my 65mm lens mounted I decided to give it another try.  I can’t say that I actually figured out the secret to getting the shot, but rather that I just lucked out and happened to have hit the shutter release at just the right moment – and with reasonable focus – as I tracked the ant along the branch on which it was crawling.  It was the only shot of one of these ants that stayed on the card that day.

The genus is huge, with 209 species occurring primarily throughout the Neotropics.  As a result, it would be foolish for me to even attempt a species ID.  Still, I can’t help noticing its great resemblance to this photo of Pseudomyrmex phyllophilus, taken by Alex in – you guessed it, Buenos Aires, Argentina.  I’ll wait for the correction, but in the off-chance that I’m right I think I deserve points on somebody’s scorecard!

Copyright © Ted C. MacRae 2011

Bichos Argentinos #1 – Eristalinus taeniops

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Eristalinus taeniops - a hover fly in the family Syrphidae

It figures that perhaps the most striking insect I saw at La Reserva Ecológica Costanera Sur in Buenos Aires, Argentina would be an introduced species, as the area itself is a man-made reconstruction of the wet Pampas grasslands endemic to coastal areas of the Rio de la Plata.  My identification of this fly as Eristalinus taeniops is based on its great resemblance to the many online photographs that exist from both South America and the U.S. and also the Old World where it is apparently native.  I found no more authoritative sources with which to confirm the ID, so this online comparative will have to do (muscophiles feel free to comment or correct). 

According to BugGuide, E. taeniops is a recent import to the U.S. from Africa, and in fact it has apparently successfully invaded much of the world.  I suppose most folks will be inclined to forgive the fly for all this because of its strikingly patterned eyes, which I would have dearly loved to have gotten in tight for a closeup.  This shot with the 100mm lens dialed in to the max (and only slightly cropped for composition), however, was the only one I managed – the fly bolted as I quickly tried to switch to the 65mm lens, and although I saw two more individuals afterwards, I couldn’t get anywhere close to them in the day’s heat.  Eyes notwithstanding, the species is a near perfect mimic of a honey bee, making one wonder what selective pressures drove the development of these fantastically contrasting eyes.

Copyright © Ted C. MacRae 2011

North America’s largest scarab beetle

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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

Brazil Bugs #15 – Formiga-membracídeos mutualismo

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Of the several insect groups that I most wanted to see and photograph during my trip to Brazil a few weeks ago, treehoppers were near the top of the list.  To say that treehoppers are diverse in the Neotropics is certainly an understatement – South America boasts an extraordinary number of bizarre and beautiful forms that still, to this day, leave evolutionary biologists scratching their heads.  The development of this amazing diversity is a relatively recent phenomenon (thinking geological scale here), as there are no known membracid fossils prior to Oligo-Miocene Dominican and Mexican amber – well after the early Cretaceous breakup of Gondwanaland split the globe into the “Old” and “New” Worlds.  With its origins apparently in South America, numerous groups continued to spring forth – each with more ridiculous pronotal modifications than the last and giving rise to the dazzling diversity of forms we see today.  Even North America got in the evolutionary act, benefiting from northern dispersal from South America’s richly developing fauna via temporary land bridges or island stepping stones that have existed at various times during the current era and giving rise to the almost exclusively Nearctic tribe Smiliini (whose species are largely associated with the continent’s eastern hardwood forests).  Only the subfamily Centrotinae, with its relatively unadorned pronotum, managed to successfully disperse to the Old World, where it remains the sole representative taxon in that hemisphere.  With a few notable exceptions, treehoppers have virtually no economic importance whatsoever, yet they enjoy relatively active study by taxonomists, evolutionists, and ecologists alike – due almost completely to the bizarreness of their forms and unique mutualistic/subsocial behaviors.

I did manage to find a few species of treehoppers during the trip (a very primitive species being featured in Answer to ID Challenge #4 – Aetalion reticulatum), and of those that I did find the nymphs in this ant-tended aggregation on a small tree in the rural outskirts of Campinas (São Paulo State) were perhaps the most striking in coloration and form.  Most were jet black, although a few exhibited fair amounts of reddish coloration, and all exhibited sharply defined white bands of wax and long erect processes on the pronotum, mesonotum, and abdomen.  I’ve seen a fair number of treehopper nymphs, but I did not recognize these as something I had seen before, and given the incomplete state of immature taxomony I feared an identification might not be possible.  Still (and I know this is probably beginning to sound like a broken record), I gave it the old college try.

I usually like to start simple and get more creative if the results aren’t satisfactory, so I went to my old friend Flickr and simply typed “Membracidae” as my search term.  Predictably, pages and pages of results appeared, and I began scanning through them to see if any contained nymphs at all resembling what I had.  After just a few pages, I encountered this photo with very similar-looking nymphs, and although no identification beyond family was indicated for the photo, I recognized the lone adult sitting with the nymphs as a member of the tribe Aconophorini – a diverse group distinguished from other treehoppers by their long, forward-projecting pronotal horn.  Luck was with me, because I happen to have a copy of the relatively recent revision of this tribe by Dietrich and Deitz (1991).  Scanning through the work, I learned that the tribe is comprised of 51 species assigned to three genera: Guayaquila (22 spp.), Calloconophora (16 spp.), and Aconophora (13 spp.).  The latter two genera can immediately be dismissed, as ant-interactions have not been recorded for any of the species in those two genera – clearly the individuals that I photographed were being tended by ants.  Further, the long, laterally directed apical processes of the pronotal horn, two pairs of abdominal spines, and other features also agree with the characters given for nymphs of the genus Guayaquila.  In looking at the species included in the genus, a drawing of a nymph that looked strikingly similar to mine was found in the species treatment for G. gracilicornis.  While that species is recorded only from Central America and northern South America, it was noted that nymphs of this species closely resemble those of the much more widely distributed G. xiphias, differing by their generally paler coloration.  My individuals are anything but pale, and reading through the description of the late-instar nymph of the latter species found every character in agreement.  A quick search of the species in Google Images was all that was needed to confirm the ID (at least to my satisfaction). 

In a study of aggregations of G. xiphias on the shrub Didymopanax vinosum (Araliaceae) in southeastern Brazil, Del-Claro and Oliveira (1999) found an astounding 21 species of associated ant species – a far greater diversity than that reported for any other ant-treehopper system.  The most frequently encountered ant species were Ectatomma edentatum, Camponotus rufipes, C. crassus, and C. renggeri, and after perusing the images of these four species at AntWeb I’m inclined to believe that the ants in these photos represent Camponotus crassus (although I am less confident of this ID than the treehoppers – corrections welcome!).  The authors noted turnover of ant species throughout the day in a significant portion of the treehopper aggregations that they observed, which they suggest probably reflects distinct humidity and temperature tolerances among the different ant species and that might serve to reduce interspecific competition among ants at treehopper aggregations.  Since treehopper predation and parasitism in the absence of ant mutualists can be severe, the development of multispecies associations by G. xiphias results in nearly “round-the-clock” protection that can greatly enhance their survival.

Update 3/3/11, 9:45 a.m.:  My thanks to Chris Dietrich at the Illinois Natural History Survey, who provided me in an email exchange some clarifying comments on the origins and subsequent dispersal of the family.  The first paragraph has been slightly modified to reflect those comments.

REFERENCES:

Del-Claro, K. and P. S. Oliveira. 1999. Ant-Homoptera interactions in a Neotropicai savanna: The honeydew-producing treehopper, Guayaquila xiphias (Membracidae), and its associated ant fauna on Didymopanax vinosum (Araliaceae). Biotropica 31(1):135–144.

Dietrich, C. H. and L. L. Deitz.  1991.  Revision of the Neotropical treehopper tribe Aconophorini (Homoptera: Membracidae).  North Carolina Agricultural Research Service Technical Bulletin 293, 134 pp.

Copyright © Ted C. MacRae 2011

Monday Moth – Polka-dot Wasp Moth

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Syntomeida epilais - polka-dot wasp moth

It’s been a while since I’ve done a Monday Moth post, so I thought I’d feature one of the prettier specimens in my very limited Lepidoptera collection.  This is Syntomeida epilais (polka-dot wasp moth), one of four species in the genus that occurs in the United States.  This particular specimen was collected by me way back in the mid-1980s (I was not quite yet the discriminating beetle collector that I am now) in Everglades National Park (yes, I had a permit).  The bright, contrasting coloration obviously screams aposematism (warning coloration), and in fact the tissues of the adult moths of this species are chock-full of several cardiac glycosides sequestered by the larva from its now preferred food plant, oleander (Nerium oleander).  Add to it their somewhat wasp-like appearance, and there should be no question to any would-be predator that these moths are a bad idea.  Wasp moths are related at the tribal level to another group of wasp-like moths called maidens which are restricted to the Old World.  I featured one of these from South Africa last year in the post, Monday Moth – Simple Maiden (Amata simplex).

If the cardiac gycosides stored in the tissues of this moth aren’t enough to cause gastric distress, trying to digest the higher taxonomic history of this group surely will.  Back in my school days, this moth belonged to the family “Ctenuchidae.”  As best I understand it, this group was later subsumed into the tiger moth family “Arctiidae” – itself later subsumed within the borg of all moth families, the Noctuidae.  In the most recent classification I’ve found, the arctiine moths have been pulled back out of the Noctuidae and combined with the former “Lymantriidae” (propelled to infamy by the gypsy moth) to form the family Erebidae (Lafontaine and Schmidt 2010).  Are you ready to purge yet? It’s still not clear to me whether this latest incarnation represents a consensus monophyletic unit, but it really doesn’t matter – whenever I see wasp moths, maidens, and especially the ctenucha moths that are so common in my area on goldenrod flowers during the fall, “ctenuchid” will still be the first name that comes to my mind.

REFERENCE:

Lafontaine, J. D. and B. C. Schmidt.  2010.  Annotated check list of the Noctuoidea (Insecta, Lepidoptera) of North America north of Mexico.  ZooKeys 40:1–239.  doi: 10.3897/zookeys.40.414

Copyright © Ted C. MacRae 2011



Brazil Bugs #14 – Fusquinha

/ Ted C. MacRae / 23 Comments


Despite their hyperdiversity, leaf beetles (family Chrysomelidae) as a group are for the most part among the most easily recognized of all beetle families, and within the family none are more recognizable than the tortoise beetles (subfamily Cassidinae).  Named for their distinctively armoured elytra and prothorax and associated behavior of drawing the head and legs under them when threatened, they are worldwide in distribution and especially diverse in the New World tropics.  Even though I know little about the group (chrysomelids as a whole are far too intimidatingly diverse a group for me to add to my already burgeoning list of interests), I can’t resist collecting them whenever I encounter them.  Having traveled to Mexico and South America many times over the years, I’ve accumulated almost a full Schmidt box of these beauties – most of which remained unidentified, save for the well-known representatives from our relatively depauperate North American fauna.


Thus, when I encountered this striking example on a leaf in the Barão Geraldo District near Campinas, Brazil, I figured the photos I took would go into one of those “Brazil Bugs” posts featuring a variety of pleasing to look at but otherwise unidentified insects.  Still, after having had success identifying some other Brazilian insects using Google, Flickr, and carefully selected search terms, I figured I should at least give this one a try.  It didn’t take long – searching on nothing more than “Cassidinae” in Flickr yielded a very similar looking beetle on page 6 from Panama identified by Rob Westerduijn as Paraselenis tersa.  While not likely the same species, it seemed almost certain to represent the same genus, so further searching on the genus name eventually led me to the cassidine mother lode: Cassidinae of the World: An Interactive Manual.  This web page, authored by Lech Borowiec, features species lists, identification keys and images of a large number of specimens, including nearly all of the 29 species currently placed in this exclusively Neotropical genus (you can bet I’m bookmarking this site – perhaps my Schmidt box of specimens will finally get some attention!).  A quick perusal through the images yielded an ID: Paraselenis (Spaethiechoma) flava, recorded broadly across South America.  Everything fit – the black scutellar marking, the elytra broader than the prothorax, the bicolored antennae, the thin black anterior elytral marginal band, and – appropriate for the species name – the even yellow coloration.  My ID was confirmed when I found a key to all the species of Paraselenis (Borowiec 2003).  I surmise this is a female based on the more rounded humeral elytral projections, which seem to be more strongly and angularly produced in the males based on the photos I looked at.


Interestingly, this particular species is considered a pest of sweet potato and commonly referred to as “fusquinha”¹ (Montes and Raga 2010).  Many species of tortoise beetles, in fact, utilize as host plants members of the sweet potato family (Convolvulaceae).  This individual was not on a convolvulaceous plant, but a small tree.  I looked for additional individuals but didn’t find any, nor did I find larvae or any evidence of feeding, so this must have been a wayward individual – probably searching for a suitable host on which to oviposit.

¹ “Fusquinha” is the Brazilian Portuguese word for “Volkswagon Beetle”!

References

Borowiec, L.  2003.  Two new species of the genus Paraselenis Spaeth, 1913 (Coleoptera: Chrysomelidae: Cassidinae).  Genus 14 (3): 403-411.

Montes, S. M. N. M. and A. Raga. 2010. “Fusquinha” Paraselenis flava (L. 1758) praga da batata-doce. Instituto Biológico – APTA, Documento Técnico 004, 8 pp..

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

.
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