beetles

A Missouri hotspot for Cylindera unipunctata

/ Ted C. MacRae / 14 Comments
Cylindera unipunctata | Gray Summit, Franklin Co., Missouri

Cylindera unipunctata | Shaw Nature Reserve, Gray Summit, Franklin Co., Missouri

Long before I began studying tiger beetles in earnest, I became aware of one of Missouri’s more interesting species—Cylindera unipunctata (one-spotted tiger beetle).  One of my favorite woodboring beetle collecting spots back in the 1980s was Pinewoods Lake Recreation Area near Ellsinore in the southeastern Ozarks.  I had stumbled upon this spot in the beginning my beetle studies and spent countless days wandering the trails through the open forest that surrounded the relatively new lake and blacklighting in the campground at night.  I literally cut my entomological teeth at this spot.  While woodboring beetles were my quarry, I couldn’t resist the few brown, apparently flightless tiger beetles (in reality, they can fly but rarely do so) that I had seen clambering across the woodland trail in front of me during one of my first visits to the area.  That following winter, when I showed them to Ron Huber during a mutual visit at the home of long-time lepidopterist Richard Heitzman (and as far as I know, owner of the largest private insect collection in Missouri), I was pleased to see his palpable excitement at my find.  I kept an eye out for this species ever since, and while I have found them in a number of localities here in Missouri—all along the eastern edge of the Ozark Highlands south of St. Louis, I’ve never seen more than one or two, or maybe three at a time.  Even when returning to spots where I had seen them previously and looking for them specifically, they seemed a rare, elusive species.  By the time Chris Brown and I had begun our serious studies of the Missouri tiger beetle fauna, I had accumulated no more than a dozen or so specimens from places like Pinewoods Lake, Hawn State Park, and Trail of Tears State Park.  Their seeming preference for shaded, woodland habitats is unusual amongst North American tiger beetles, save for the conspicuous and commonly encountered Cicindela sexguttata (six-spotted tiger beetle), but within that habitat I had begun to notice a commonality—open woodland with steep rocky/clay slopes.

Beetles are quick to take cover in the leaf litter

Beetles are quick to take cover in the leaf litter

A few years ago, Chris Brown noticed that this species seemed to be fairly common at Shaw Nature Reserve in Gray Summit, Missouri.  I was surprised to learn of the occurrence of this species just 40 miles southwest of St. Louis (and only 15 miles from my home), and in 2009 I resolved to go there and see it for myself.  I had just begun digital insect photography at the time as well, so I was looking forward to the chance to photograph one of Missouri’s rarer tiger beetles.  On the first trip to SNR in May 2009, I searched the trails repeatedly where Chris had seen them but never saw a single one.  I thought maybe I was too early, so I went back a couple of weeks later at the end of May, and this time I found one… but just one!  I got off a series of shots before the beetle bolted and eventually disappeared, leaving me with one decent shot of the species.  The lighting and focus in the photo were good, but the photo was just… well… boring!

Adults were most frequent along sloping portions of the trail.

Adults were most frequent along sloping portions of the trail.

A few weeks ago, again near the end of May, I decided to try for the species again.  I’ve now been photographing tiger beetles for two years rather than two weeks, so perhaps I’ve learned a few tricks in locating and photographing the beetles that would give me a better variety of photos to show for my effort.  I went back to the same trail (Jane’s Wildflower Trail), and while I did have better luck (finding four beetles instead of just one) I was still not happy with the photos I had gotten to that point (only Photo #2 is from that session).  I decided to try my luck along another trail (Bluff Overlook Trail) where James Trager had seen an individual earlier just that week.  At first, the beetles seemed to have the same fairly low occurrence that they had along the first trail.  Still, I saw enough individuals to get a number of photos that I was happier with (#1, #3 and #4 in this series), and I figured the job was done.  We hiked down towards the river to see if we might find the population of Cicindela formosa generosa that Chris had seen on a sand bar in a previous year, but flooding by the Meramec River had much of the area—and certainly any open sandy areas—under water.

Beetles were less skittish when hidden amongst small plants.

Beetles were less skittish when hidden amongst small plants.

By the time we took the trail back up to the higher elevations it was getting later in the afternoon, and I returned to keeping an eye out for the tiger beetles.  As soon as we returned to the steep, rocky clay slope areas where I had seen the few earlier beetles, I started seeing them in decent numbers.  I had enough photos by then, so I collected a few more individuals to beef up the voucher series, and as we walked it seemed the beetles became more numerous with each step.  Then I saw something I had not seen all day—a mating pair!  I carefully setup for the shot, but I disturbed them in the process and they split up.  However, dejection quickly turned to elation, as almost immediately I saw another mating pair.  This time I made no mistakes and got in a few shots before they broke up and split.  As I was photographing them, I saw another mating pair perched on a nearby rock—I liked them even better, and the shot below is my favorite of that pair.  Over the next half hour, we saw countless adults and mating pairs.  Part of me wonders if it was the time of day, as the species is reported to be more active during late afternoon (Pearson et al. 2006).  I do note that all of my visits to Jane’s Wildflower Trail have been during morning and early afternoon, so perhaps they are just as common along that trail as well and I have just never been there at the right time of day to see that.

Mating pairs were seen with greater frequency during late afternoon.

Mating pairs were seen with greater frequency during late afternoon.

While most of the adults I saw were on the Bluff Overlook Trail, one thing I did find in numbers along Jane’s Wildflower Trail were larval burrows.  Their location was consistent with the habitat noted by Hamilton (1925), who described the larvae from specimens dug from bare, rocky soil on a steep, sparsely wooded hillside.  I returned the next morning to the spot where I had seen the larval burrows and was able to extract four larvae from their burrows by digging them out and have set them up in a rearing container of native soil.  I can’t yet rule out the possibility that they might represent C. sexguttata, which occurs commonly in the area; however, all signs—the depth of the burrows (only 3 to 4 inches), their occurrence on steep, rocky slopes, the open woodland—point to them belonging to C. unipunctata.

Larval burrows were located on steep rocky/clay slopes in open woodland.

Cylindera unipunctata may truly be more common across its range (eastern North American forests) than is realized.  In contrast to C. sexguttata, and despite their shared woodland habitat, C. unipunctata is somber colored, avoids sunlit spots, rarely flies, and shows a distinct preference for staying within the leaf litter.  These features make the beetles easily overlooked, even by experienced tiger beetle collectors.  Frank Guarnieri (2009) recently published a note describing a “hot spot” for this species in Maryland, in which he described an encounter with innumerable individuals in a Maryland state park from late May through June.  This encounter was all the more remarkable considering that he had only seen two individuals during the previous ten years.  I tend to agree with his assertion the scarcity of C. unipunctata is probably more apparent than real—an artifact of its cryptic habits, short temporal occurrence, and fairly specific habitat preferences that are atypical amongst most tiger beetle species.

REFERENCES:

Guarnieri, F. G.  2009.  Observations of Cicindela unipunctata Fabricius, 1775 (one-spotted tiger beetle) at Pocomoke River State Park, Worcester County, Maryland.  The Maryland Entomologist 5(1):2–4.

Hamilton, C. C.  1925.  Studies on the morphology, taxonomy, and ecology of the larvae of Holarctic tiger beetles (family Cicindelidae).  Proceedings of the U. S. National Museum 65(17):1–87.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

Dromochorus pruinina is not extirpated in Missouri… yet!

/ Ted C. MacRae / 7 Comments

ResearchBlogging.orgWhen Chris Brown and I began our study of Missouri tiger beetles back in 2000, our goal was simply to conduct a faunal survey of the species present in the state.  Such studies are fairly straightforward—examine specimens in the major public and private collections, and do lots and lots of collecting, especially in areas with good potential for significant new records.  Over the next 10 years, however, our study morphed from a straightforward faunal survey to a series of surveys targeting a number of species that seemed in need of special conservation attention.  We were no longer just collecting tiger beetles, but trying to figure out how to save them.

There were good reasons for this—Missouri’s tiger beetle fauna is rather unique due to the state’s ecotonal position in the North American continent.  While its faunal affinities are decidedly eastern, there are also several Great Plains species that range into the state’s western reaches.  Even more interestingly, these western species occur in Missouri primarily as relict populations—widely disjunct from their main geographic ranges further west, and limited in Missouri to small geographical areas where just the right conditions still exist.  These include the impressive (and thankfully secure) Cicindela obsoleta vulturina (prairie tiger beetle), the likely extirpated Habroscelimorpha circumpicta johnsonii (Johnson’s tiger beetle, with Missouri’s disjunct population often referred to as the ‘saline spring tiger beetle’), Cylindera celeripes (swift tiger beetle)—still clinging precariously to existence throughout much of its former range, and the subject of our newest publication, Dromochorus pruinina (frosted dromo tiger beetle) (MacRae and Brown 2011).

We were first made aware of the occurrence of this species in Missouri when Ron Huber (Bloomington, MN) sent us label data from 7 specimens in his collection.  One was labeled from Columbia, Missouri—location of the University of Missouri, and source of many a mislabeled specimen culled from collections of entomology students.  The other specimens, however, collected in 1975 and labeled “10 miles W of Warrensburg” in western Missouri, seemed legit, and in 2003 we began searching in earnest for this species.  Our searches in the vicinity of 10 miles W of Warrensburg were not successful (and, in fact, we had difficulty even locating habitat that looked suitable), but on 15 July 2005 Chris found the species on eroded clay roadsides along County Road DD in Knob Noster State Park—precisely 10 mi east of Warrensburg.  With this collection as a starting point, we began an intense pitfall trapping effort in 2006 to more precisely define the geographical extent of this population in Missouri.  The Knob Noster population was confirmed at several spots along the 2.5-mile stretch of Hwy DD that runs through Knob Noster State Park, but we were surprised to find no evidence of this species at any other location throughout a fairly broad chunk of west-central Missouri (see Fig. 1 above).  We examined the area thoroughly in our search to find suitable habitats for placing pitfall traps, and it became quite obvious that the eroding clay banks that harbored the species in Knob Noster State Park were not extensive in the area.  This observation also seemed to further confirm our suspicion that the label data for the original 1975 collection were slightly erroneous, and that the Knob Noster population was, in fact, represented by that original 1975 collection.

In 2008, we conducted additional pitfall trapping surveys tightly concentrated in and around Knob Noster State Park.  Again, we only found the beetle along the same 2.5-mile stretch of Hwy DD, despite the presence of apparently suitable eroded clay roadsides in other parts of the park.  These other areas were either disjunct from the Hwy DD sites, separated by woodlands that this flightless species likely is not able to traverse, or were fairly recently formed through road construction activities.  These newly formed bare clay roadsides were quite close to the beetle sites, and we are still hard pressed to explain why the beetle has apparently not yet colonized them—perhaps there is some physical or chemical property that the beetle requires that is not present in these more anthropogenically formed habitats.  Whatever the explanation, the result is the same—the entire Missouri population of D. pruinina appears to be restricted to a scant 2.5-mile stretch of roadside habitat in west-central Missouri, disjunct from the nearest population further west (Olathe, Kansas) by a distance of 75 miles.  The highly restricted geographical occurrence of this species in Missouri is cause enough for concern about its long-term prospects, but the relatively low numbers of adults that were encountered—38 throughout the course of the study—is even more troubling.  Dromochorus pruinina is not extirpated in Missouri, but the prospect of such is a little too real for comfort.

As a result of our studies, D. pruinina is now listed as a state species of conservation concern with a ranking of “S1” (critically imperiled)—the highest possible ranking (Missouri Natural Heritage Program 2011).  Despite its highly restricted range in Missouri, the occurrence of this population entirely within the confines of Knob Noster State Park under the stewardship of the Missouri Department of Natural Resources (MDNR) provides some measure of optimism that adequate conservation measures will be devised and implemented to ensure the permanence of this population.  Chief among these is the maintenance of existing roadside habitats, which are kept free of woody vegetation by a combination of mowing and xeric conditions.  True conservation of the beetle, however, can only occur if the area of suitable habitat is significantly expanded beyond its present extent.  Much of the park and surrounding areas are heavily forested and, thus, do not provide suitable habitat for the beetle.  Significant areas within the park have been converted in recent years to open woodlands and grasslands; however, these areas still possess a dense ground layer and lack the patchwork of barren slopes that seem to be preferred by the beetle.  Further conversion of these areas to grasslands with more open structure will be required to create additional habitats attractive to the beetle.  Until this is done, D. pruinina is at risk of meeting the same fate that has apparently befallen the Missouri disjunct population of H. circumpicta johnsonii (Brown and MacRae 2011).

REFERENCES:

Brown, C. R. and T. C. MacRae.  2011.  Assessment of the conservation status of Habroscelimorpha circumpicta johnsonii (Fitch) in Missouri.  CICINDELA 42(4) (2010):77–90.

MacRae, T. C. and C. R. Brown. 2011. Distribution, seasonal occurrence and conservation status of Dromochorus pruinina (Casey) in Missouri CICINDELA 43(1):1–13.

Missouri Natural Heritage Program.  2011.  Species and Communities of Conservation Concern Checklist.  Missouri Department of Conservation, Jefferson City, 52 pp.

Copyright © Ted C. MacRae 2011

Bichos Argentinos #13 – Spotted Maize Beetle

/ Ted C. MacRae / 9 Comments

Astylus atromaculatus (spotted maize beetle) | Inés Indart, Argentina.

One of the most common insects encountered in agricultural fields in Argentina is Asylus atromaculatus (spotted maize beetle).  This native species can also be found further north in Bolivia and Brazil, and as implied by its common name it is frequently encountered in maize fields.  The species, however, is also common on soybean, on which the individual in the above photo (and mating pair in the previous post) were found.  Looking like some strange cross between a checkered beetle (family Cleridae) and a blister beetle (family Meloidae), it is actually a member of the Melyridae (soft-wing flower beetles)—placed with the Cleridae in the superfamily Clerioidea.

Despite its abundance (and the resultant attention it gets from growers), the pollen feeding adults are of little economic importance.  It’s easy to see, however, why this species gets so much attention from growers—during January through March the adults occur in tremendous numbers, congregating on a wide variety of flowering plants, but especially corn. Their large numbers are an impressive sight, with literally dozens to even hundreds of adults occurring on a single plant. Tassles—the source of corn pollen—are highly preferred, but when populations are heavy the silks and any exposed ears are also popular congregation sites. Despite their numbers, the impact of the beetles on yield is rarely sufficient to warrant the cost of control measures.


Whatever economic impact the species might have is actually due more the larvae—hidden within soil—than to the super-abundant and highly conspicuous adults. Feeding primarily on decaying plant matter within the soil, larvae do occasionally attack newly planted corn, either before or just after germination. Their attacks are more common in dry years and in severe cases can lead to the need to replant a field. This seems to be more common in South Africa, where the species was introduced in the early 1900s, than in its native distribution in South America.


Whenever I see a ubiquitous, diurnal, brightly and contrastingly colored insect, the first suspicion that comes to my mind is aposematic (warning) coloration and chemical defense against predation. There seems to have been some investigation into the toxicity of this species (Kellerman et al. 1972), and in South Africa they have been implicated in poisoning of livestock when accidentally ingested with forage (Bellamy 1985).  Few other reports of toxicity by beetles in this family are known, but four species of the genus Choresine have been shown to produce high levels of batrachotoxin alkaloids—these are the same toxins found in the skin of poison-dart frogs of the genus Phyllobates (Dumbacher 2004).  The frogs are unable to synthesize these toxins themselves, thus, it is presumed that they sequester these compounds from their diet—whether it is from some species of Melyridae remains to be determined.

Congratulations to Alex Wild and Max Barclay, who both answered the call to ID Challenge #8 and correctly determined all taxa from order to species.  Alex, by way of submitting his ID first, gets a bonus point and leads the current BitB Challenge session with 9 points.  Thanks to the rest who played along as well—see my response to your comments for your points earnings.

REFERENCES:

Bellamy, C. L. 1985.  Cleroidea, pp. 237–241.  In: Scholtz, C. H. and E. Holm (Eds.), Insects of Southern Africa, Butterworths, Durban.

Dumbacher, W. A., S. R. Derrickson, A. Samuelson, T. F. Spande and J. W. Daly. 2004.  Melyrid beetles (Choresine): a putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds.  Proceedings of the National Academy of Sciences, USA 101(45):15857–15860.

Kellerman, T. S., T. F. Adelaar and J. A. Minne. 1972. The toxicity of the pollen beetle Astylus atromaculatus Blanch. Journal of the South African Veterinary Medical Association 43(4):377–381.

Copyright © Ted C. MacRae 2011

Big, Bold, and Beautiful

/ Ted C. MacRae / 12 Comments

Cicindela formosa generosa | Castlewood State Park, Missouri.

Last fall I took my younger daughter to the Al Foster Trail on the western side of Castlewood State Park, just a few miles down the road from my house.  As we walked the trail through typical bottomland forest next to the Meramec River, I noticed what appeared to be open ground on a rise to the north of the trail.  When I went up to investigate, I saw a rare sight for Missouri—dry sand!  Obviously a deposit from some past flood event, the post oaks established around its perimeter and native warm season grasses sparsely dotting its interior suggested it had been laid down many years ago.  Such sights were likely common along the big river systems of pre-settlement Missouri, as natural flooding cycles laid sand deposits up and down the river courses, each deposit gradually succumbing to vegetation as new deposits were laid down elsewhere.  Today, with channelization and levees for flood control, the Missouri and Mississippi Rivers are just narrow, hemmed-in shadows of their former selves, unable to lay down such deposits in most years until, at last, catastrophic flooding occurs on a grand scale (as is occurring now).  Feeding into the Mississippi River just south of the Missouri River is the Meramec River—as the state’s only still-undamned undammed river system, it still has opportunity on occasion to lay down these interesting dry sand habitats.

The dark brown coloration of this rather ''dirty'' individual is typical of most Missouri populations.

When I see dry sand habitats in Missouri, three tiger beetle species immediately come to mind—Cicindela formosa (big sand tiger beetle), C. scutellaris (festive tiger beetle), and Ellipsoptera lepida (ghost tiger beetle).  My colleague and co-cicindelophile Chris Brown and I have spent many a weekend traveling up and down the state’s river systems with these species in mind.  None of them are rare in the state, but their fidelity to deep, dry sand habitats also makes them by no means common.  It is always cause for celebration when a new site is discovered for one of these species somewhere in Missouri.  Thus, it was in anticipation of one (or more) of these species that I returned to the spot last week on the first truly gorgeous spring day of the season.  Could it really be that, after ten years of searching for these species throughout the state, I would find a population just a few miles down the road from my house?!

A number of individuals in this population show traces of the bright coppery red coloration more typical of nominotypical populations west of Missouri.

Walking onto the site, I began to see tiger beetles immediately.  However, they were Cicindela tranquebarica (oblique-lined tiger beetle), a common species in Missouri that enjoys not only dry sand habitats, but also wet sand, wet mud, dry clay, and even concrete habitats—hard to get excited about such a habitat slut!  Nevertheless, within minutes I began seeing more robust beetles that were unmistakably big sand tigers.  Big, bold, and beautiful, the beetles were wary in the late afternoon heat and quickly launched into their powerful escape flights that ended comically some 20 yards away with a characteristic bounce and a tumble.  Such behavior might seem to make them impossible to photograph, but I’ve been at this for awhile and know their behavior pretty well—a slow, cautious approach, crouching carefully at the right distance, and crawling deliberately on elbows and knees while peering from behind the camera until it shows up in the lens set to 1:3 (one-third life size).  Then it’s a matter of even more slowly closing the distance and scooting around to get the desired angles and composition.  Move slowly enough and they’ll forget you’re there and resume normal behavior—you’ll be richly rewarded with views of foraging, stilting, and other classic tiger beetle behaviors.

Coloration and markings may seem conspicuous but provide excellent camouflage against the pebbley-sand substrate.

Most of the big sand tiger beetle populations we have found in Missouri are typical of the eastern subspecies C. formosa generosa, distinguished from other named subspecies by the dark brown dorsal coloration and thick white markings that are separate dorsally and joined along the outer edges of the elytra (Pearson et al. 2006).  This subspecies is predominantly midwestern and northeastern in distribution, while the typically bright coppery-red individuals assigned to the nominotypical subspecies are found further west in the Great Plains.  There are, however, certain populations in Missouri that show more or less suffusion of coppery-red coloration.  This is typically explained as hybrid influence, as Missouri lies on the western edge of the distributional range of subspecies generosa.  However, we have only seen these coppery-red indications on the eastern side of Missouri, while populations on the western side of the state along the Missouri River exhibit typical dark brown coloration.  The population here in St. Louis Co. is the third population we have found to show this coppery-red influence, and in fact most of the individuals I saw exhibited greater or lesser amounts of this coloration.  My personal belief is that there is no genetic basis for this subspecific distinction, but that the differences in color are instead related to conditions of the soil in which they live—possibly pH.  Sand habitats in the eastern United States are typically acidic, while alkaline soils abound in the Great Plains (formerly a vast sea bottom).  Hey, it’s a thought!

Big sand tiger beetles remain one of my favorite beetle species in Missouri.

The combination of striking coloration and bold white markings exhibited by big sand tiger beetles might seem to make them quite conspicuous and vulnerable to predation—especially in the open, sparsely vegetated areas that they inhabit; however, against the textured sandy substrates on which they are found they are almost impossible to detect until they move.  I’ve learned not to try to see them first and sneak up on them, as this is a lesson in futility.  Rather, I simply walk through an area and fix my sights on individuals as they take flight, watching them as they fly and eventually land and then sneaking up to the spot where I saw them land.  I generally need to stop about 8-12 feet out and study the spot carefully to pick them out, and then I can continue sneaking up on them.

Photo Details: Canon 50D w/ 100mm macro lens (ISO 160, 1/200 sec, f/16), Canon MT-24EX flash w/ DIY oversized concave diffuser. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCES:

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

Copyright © Ted C. MacRae 2011

Feasting on the bounty

/ Ted C. MacRae / 16 Comments

Brood XIX periodical cicadas were not the only insects appearing en masse last week at Sam A. Baker State Park in Missouri’s southeastern Ozark Highlands.  As I walked the upland trail, I thought I felt ‘raindrops’ for awhile before realizing that it was frass.  Little pieces of fresh young leaves littered the trail around me, and I realized that an outbreak of caterpillars was hammering the oak trees in this forest.  Unlike the cicadas, which were encountered primarily in the bottomland forest along Big Creek, the rain of poop was restricted to the uplands.  Not surprisingly, I saw caterpillar hunters, Calosoma spp. (family Carabidae—the real Carabidae, not the tiger beetle Carabidae that I’ve begrudgingly had to accept) about as abundantly as I’ve ever seen them.  At first I didn’t notice them until I would scare one up, then spend several frustrating minutes trying to photograph a beetle that just would not stop running.  I tried a few and gave up—after all, they’re just ground beetles (i.e., real ground beetles).  Eventually, I realized that if I noticed them before they noticed me, I could sneak up on them and have my way with them (photographically speaking, that is).  I even found that I could preen nearby leaves and sticks for composition if I did it carefully enough.  Here are a couple of my favorite shots on the day.

I would presume these to represent the fiery searcher, Calosoma scrutator, but apparently C. wilcoxi is similar in appearance.  According to comments by several BugGuide users, C. scrutator is larger (25mm or more in length), has more elongated mandibles and head, and the color of the central purple area of the pronotum is more intense.  Based on those comments, I would say the two individuals in these photographs are C. scrutator.  However, they also note some differences in temporal occurrence that don’t seem to support that.  Moreover, the many individuals I saw that day ranged in size from these larger individuals to some notably smaller ones.

Copyright © Ted C. MacRae 2011

Love is in the air!

/ Ted C. MacRae / 14 Comments

My first tiger beetle photograph of the season. There’s nothing more adorable than Spring love!

Cicindela tranquebarica (oblique-lined tiger beetle) | St. Joe State Park, Missouri

Photo details: Canon 50D w/ 100mm f2.4 macro lens (ISO 160, 1/200 sec, f/16), Canon MT-24EX twin flash w/ DIY oversized concave diffuser.

Copyright © Ted C. MacRae 2011

Bichos Argentinos #11 – Takes Two to Tango

/ Ted C. MacRae / 10 Comments

Epilachna vigintioctopunctata (vaquita de las solanáceas) | Buenos Aires, Argentina

Another of the insects that I photographed at La Reserva Ecológica Costanera Sur, Buenos Aires, Argentina during my early March visit.  I found quite a few of these beetles feeding on the newly sprouting growth from cut stumps of a small, multi-stemmed tree.  At first I thought they were leaf beetles of the family Chrysomelidae because of the way they were actively feeding on the fresh, succulent growth; however, a closer look quickly revealed them to be members of the family Coccinellidae (ladybird beetles).  Their phytophagous, gregarious behavior immediately identified them as members of the subfamily Epilachninae, and in fact they bear a remarkable resemblance to Epilachna varivestis (Mexican bean beetle) and E. borealis (squash lady beetle) – the best known examples of this subfamily in North America.

Armed with confidence in at least a subfamilial placement, I looked for references on the group and quickly found a reasonably recent revision of the subfamily for the entire Western Hemisphere (Gordon 1975) – jackpot!  I reasoned an abundant species seen in the heart of the 3rd largest city in South America would likely show up on page one, but after several increasingly careful passes through the entire revision, it became clear that whatever species this was, it was not among the nearly 300 species (2/3 of them in the genus Epilachna) treated in that work. 

Now, the exuberant, young, not-very-sage entomologist that I was 30 years ago would have immediately gotten all excited that I had found a new species, but the older, battle-tested, more cautious entomologist that I am now instead started suspecting I was dealing with an introduced species.  After all, some of the insects and plants I’ve already featured from this man-made nature reserve are introduced.  I figured as abundant as the beetles were, the species had to be featured on some website, so I started with the obvious and Googled “Coccinellidae Argentina,” clicked on the very first result (appropriately titled Coccinellidae of Argentina), and found a seemingly authoritative site with links to the different subfamilies.  Clicking on Epilachninae and scanning the photos, there it was – Epilachna vigintioctopunctata (28-spotted ladybird beetle).  Native to India and southeastern Asia, this species is well known for its attacks on numerous solanaeous and cucurbitaceous crops (Richards 1983).  It made its first appearance in the Western Hemisphere in southern Brazil (Schroder et al. 1993) and in 1994 was observed on experimental eggplant plots at the School of Agronomy, University of Buenos Aires (Folcia et al. 1996).  Poetically, those initial specimens were sent to Robert Gordon at the U.S. National Museum (and author of the Western Hemisphere revision), who confirmed their identity.  It seems that Argentinians are not the only ones that like to tango!

REFERENCES:

Folcia A. M., S. M. Rodriguéz and S. Russo. 1996. Aspectos morfológicos, biológicos y de preferencia de Epilachna vigintioctopunctata Fabr. (Coleoptera Coccinellidae). Boletin de Sanidad Vegetal Plagas 22:773–780.

Gordon, R. D. 1975. A revision of the Epilachninae of the Western Hemisphere (Coleoptera: Coccinellidae). U. S. Department of Agriculture, Technical Bulletin No. 1493, ii+409 pp.

Richards, A. M.  1983.  The Epilachna vigintioctopunctata complex (Coleoptera: Coccinellidae).  International Journal of Entomology 25(1):11–41.

Schroder, R. F. W., M. M. Athanas and C. Pavan. 1993. Henosepilachna vigintioctopuctata (Coleoptera-Coccinelidae), new record for Western Hemisphere, with a review of host plants. Entomological News 104(2):111–112.

Copyright © Ted C. MacRae 2011

Bichos Argentinos #11 – I’m out’a here!

/ Ted C. MacRae / 4 Comments

Neither of these photos are very good, but it’s the firefly’s fault.  I saw it last month in a soybean field in Buenos Aires Province, Argentina. I got off the first shot, but the flash disturbed it and it started walking around. I quickly set up for another shot, got it framed, fired the shot, and saw the second photo on the screen!

Everything about this firefly seems backwards – most fireflies are black with yellow, orange or red markings – this one is yellow with small black markings.  The terminal segments of the abdomen are dark while the rest are light – opposite of most other fireflies.  This one was out and about during the day, while most others are crepuscular or nocturnal.  Maybe it’s a result of being in the Southern Hemisphere – opposite of most other fireflies I’ve seen.

Copyright © Ted C. MacRae 2011