Arthropoda

Arthropods – insects, arachnids, crustaceans, myriapods, & relatives

Zygogramma Desmogramma leaf beetles in Argentina

/ Ted C. MacRae / 12 Comments


The east end of  in Buenos Aires offers a quiet contrast to the more populated central and western areas. Few people leave the levee-trail system that surrounds the famous wetlands and pampas grass stands in those latter areas; however, those that do find in the east a mosaic of pastures and young woodlands that offer a greater diversity of sights and invite a more leisurely pace. November is spring in Buenos Aires, and as such there were a number of plants beginning to bloom in the Reserve. One plant I found blooming in abundance in one small part of the east area was a member of the family Malvaceae that I take to be Abutilon pauciflorum, a few of which were being devoured by these leaf beetles (family Chrysomelidae).


These beetles are clearly members of the subtribe Doryphorina within the nominate subfamily, looking very similar to the North American species Zygogramma suturalis (ragweed leaf beetle) or the vittate species of Calligrapha (subgenus Bidensomela), e.g. Calligrapha bidenticola. Both of these genera are represented in Argentina, and at first I was inclined to believe the beetles belonged to the latter genus since its Central and South American members are associated almost exclusively with malvaceous plants (North American species of Calligrapha have adapted to plants in several other families). However, a view of the tarsus in the last photo suggests that the claws are joined at the base, a character that immediately separates members of the genus Zygogramma from the genus Calligrapha (species of Doryphora also have fused tarsal claws but exhibit a completely different gestalt). Eight species of Zygogramma have been recorded from Argentina, but I wasn’t able to find photographs of any that look reasonably similar to the individuals in these photos.  The identification will have to remain, frustratingly, non-specific.

Update 12/6/11: I just received an email from Shawn Clark (Brigham Young University, Provo, Utah) saying that he suspects the beetles belong to the genus Desmogramma. This genus is distinguished from both Zygogramma and Calligrapha by having the prosternum sharply angled upward anterior to fore coxae or mesosternum with a distinct horn directed anteriorly (Flowers 2004) and the claws widely separated and unarmed. Unfortunately, neither character is visible in these photos. Three species of Desmogramma are recorded from Argentina, and the coloration of these individuals resembles that described by Stål (1862) for D. striatipennis (D. semifulva and D. nigripes have the 3rd, 5th and 9th elytral interstices light).


These photographs represent continued efforts with the so-called ‘blue sky background’ technique that I’ve been trying to perfect as an alternative to the black background one typically gets in insect macrophotography with full-flash illumination of the subject. All of these photos were taken at ISO 640 using an MP-E 65mm lens at f/13 with 1/160 sec (1st photo) or 1/125 sec (2nd and 3rd photos) exposure and F.E.C. -1. These are similar settings to those used in my previous and not as satisfactory attempt, but this time the results were much better. Not only is the color of the sky spot-on blue, but these photos have much better detail than the previous. In this case, I believe “locking'” the subject relative to the lens to prevent motion blur was the key—I used my left hand to hold the leaf with the beetle towards the bluest area of the sky, rested the camera lens on my left wrist, used my fingers to fine tune the leaf position as I looked through the viewfinder, and held my breath!

REFERENCE:

Flowers, R. W. 2004. The genera of Chrysomelinae (Coleoptera: Chrysomelidae) in Costa Rica. Revista de Biología Tropical 52(1):77–83.

Stål, C. 1862. Monographie des Chrysomélides l’Amérique. C. A. Leffler, Upsal, 365 pp.

Copyright © Ted C. MacRae 2011

Return to La Reserva Ecológica Costanera Sur

/ Ted C. MacRae / 14 Comments

Last March I discovered —a gem of natural beauty in the heart of Buenos Aires, Argentina.  Though its origins are semi-artificial, its biota a mix of native and introduced species, and its pathways continually choked with pedestrians and cyclists, for me it is a refuge—a place where I can spend an entire day looking for insects without ever retracing my footsteps.  Last Sunday after arriving in Buenos Aires, I couldn’t check into my hotel and change into my “bug collecting clothes” fast enough before making a beeline to the Reserve just a few blocks away.  I “discovered” a huge area on the east side of the Preserve that I hadn’t found during my last visit that was devoid of paved paths—and thus people—and spent the next several hours rummaging through the brush looking for insects to photograph.  Early November is early spring in Buenos Aires, and insect activity was still just beginning.  I did find a number of insects to photograph, though not as many as I had found during my early March visit.

This butterfly, which I regard as Actinote carycina (Yellow Lazy), was common around stands of a purple-flowered plant.  I watched this particular individual flit endlessly back and forth in front of one particular stand, rarely pausing long enough to allow a shot or two before resuming its patrols.  Vigorous aerial battles ensued every time another individual approached the stand, and although I can’t say for sure that it was this individual that always won, the same patrolling flight pattern resumed as soon as one of the contestants flew away.

Beetles were scarce, but I saw this particular species of Melyridae (presumably in the genus Astylus, and thus a close relative of Astylus atromaculatus or “spotted maize beetle”).  I don’t normally do random “bug-on-a-flower” photos, but I’ve recently become enamored with the use of “blue sky technique” for insect macrophotography and thought the red and black color of the beetle against the yellow flower it was feeding on was well suited for a blue background.  The beetle was quite small (only ~6 mm in length), thus requiring the 65mm 1–5X lens and full-flash illumination.  Normally this would result in a black background unless something is placed behind the subject, and I suppose I could just carry around a colored cards for placing behind subjects to get whatever color background I want.  However, there is something appealing to me in having the ability to achieve a blue sky by actually using the sky, despite the trickiness of the technique.  In this case, I  played with ISO settings of 400–640 and shutter speeds of 1/100 to 1/125 sec (settling at the high end of each range for this photo) to get the color of the sky true, then used low F.E.C. settings (-1 2/3 in this case) to temper the illumination of the subject.  I’m still not completely happy with the results—there is more motion blur in the photo than I would like, and I burned the yellows a little too much as well.  I think ISO800 and F.E.C. -2 or even lower would have given better results.  At any rate, this photo was the best of the bunch, and it will have to do.

Copyright © Ted C. MacRae 2011

“Sunflower looper” – Rachiplusia nu

/ Ted C. MacRae / 11 Comments

Rachiplusia nu ''oruga medidora'' | Santa Fe Province, Argentina

With a planted area approaching 20 million hectares, soybean has become Argentina’s most important agricultural crop.  Most of the planted area is located within the so-called “Humid Pampas” region of central Argentina (Buenos Aires, Córdoba, Santa Fe and Entre Rios Provinces), but the crop continues to expand in the northestern part of the country as well (Chaco, Tucumán and Salta Provinces).  More than any other crop in Argentina (except perhaps cotton), soybean is attacked by a tremendous diversity of insects.  The most important of these are the defoliating Lepidoptera, primarily species in the family Noctuidae.  Anticarsia gemmatalis (velvetbean caterpillar) is the most consistent and widespread defoliator, but an increasingly important species in Argentina is Rachiplusia nu (“oruga medidora del girasol,” or sunflower looper).

Eggs are laid primarily on the undersides of leaves

Rachiplusia nu belongs to the noctuid subfamily Plusiinae, the larvae of which can be recognized by having three pairs of prolegs and the “looping” manner by which they walk.  Chrysodeixis includens¹ (soybean looper), much better known because of its status as a major pest of soybean in the southeastern United States (and of growing importance in Brazil as well), also belongs to this group, and in fact the larvae of the two species are quite similar in appearance.  While R. nu is the primary plusiine species affecting soybean in Argentina, C. includens has appeared with increased frequency on soybean in Argentina in recent years, primarily in the more northern, subtropical growing regions adjacent to those areas in Brazil where it is now a major pest of the crop.

¹ Although still widely referred to in the literature as Pseudoplusia includens, the genus Pseudoplusia was synonymized under Chrysodeixis some eight years ago by Goater et al. (2003).  More recently the synonymy was accepted and formally applied to the North American fauna by Lafontaine and Schmidt (2010). 

Neonate larva on soybean

Despite their similarity of appearance, larvae of the two species can be rather conclusively distinguished by the shape of their spinneret (Angulo and Weigert 1975).  This is not a very convenient character for use in the field, however, leading to misidentifications in areas where the two species co-occur.  This is not an insignificant problem, as the two species exhibit differing susceptibilities to pesticides labeled for their control (C. includens especially having become resistant to a number of pesticides).  The result is control failures and subsequent application of even more pesticides in an effort by farmers to protect their crops.  While not as conclusive as the shape of the spinneret, in my experience R. nu larvae (at least older larvae) tend to have a darker, smoky-blue cast to the color (compared to the bright yellow-green of C. includens) and rather distinct patches of tiny black asperites on the thoracic ventors that are not apparent in C. includens.

Younger larvae consume only the lower surface between veins, resulting in ''window paning''

As the common name implies, soybean is not the only crop attacked by R. nu.  Early season infestations tend to occur in alfalfa and flax, after which the populations spread to soybean and sunflower.  The latter crop especially is heavily attacked by this insect, primarily in the drier western regions in Córdoba Province.  Dry conditions seem to favor an increase in the populations of this species, while moist conditions promote increased incidence of pathogenic fungi that are very effective at suppressing R. nu larval populations.

Older larvae consume entire tissues but still avoid veins, resulting in a ''skeletonized'' appearance

Like many defoliating lepidopterans, eggs tend to be laid on the undersides of leaves, where the larvae begin feeding after they hatch.  Young larvae consume only the lower epidermal layer of the foliage between the veins, leading to an appearance in the foliage called “window paning”.  As they larvae grow they begin consuming the entire tissue layer but still preferentially avoid vascular tissue, resulting in a skeletonized appearance to the foliage.  A single larvae can consume more than 100 cm² of soybean foliage, which translates to several trifoliates.  As a result, it doesn’t take many larvae to cause significant loss of foliage on the plant.  Soybean has the ability to compensate for loss of foliage due to increased photosynthesis in lower foliage exposed by feeding in the upper part of the plant, but losses exceeding around 15% during the later reproductive stages of plant growth are enough to significantly reduce yields (and it is during these reproductive stages of growth that R. nu infestations tend to occur).

Rachiplusia nu adult | Buenos Aires Province, Argentina

Rachiplusia nu is the most widely distributed of three South American species in the genus, occurring in Argentina, Bolivia, Brazil, Chili, Paraguay, Peru and Uruguay, while a fourth species, R. ou, is widely distributed throughout North and Central America (Barbut 2008).  Unlike R. nu, its North American counterpart R. ou has not gained status as a pest of soybean or other crops.

In a BitB Challenge first, nobody was able to correctly ID the larva of this species beyond the level of subfamily.  This, despite the huge Argentina hint bomb that I dropped when I posted the challenge and my well-known vocation as a soybean entomologist.  I figured the answer would be forthcoming as quickly as one could Google the search phrase “Argentina soybean Plusiinae” (which, in fact, shows the following except for the very first result “Pseudoplusia includens is the most common soybean Plusiinae in the Americas (Herzog, 1980). Rachiplusia nu in southern Brazil, Uruguay and Argentina, and…” [emphasis mine]). Most participants guessed, predictably, soybean looper, while only a few were fooled into guessing Geometridae (the true loopers, and distinguished by having only two pairs of prolegs).  As a result, I’m not declaring a winner for ID Challenge #14, although the appropriate points will still be awarded (when I get around to assigning them, that is.  Hey, I’m working in Argentina right now—it was enough for me just to get this post out!).

REFERENCES:

Angulo, A. O. and G. T. H. Wiegert. 1975. Estados inmaduros de lepidópteros noctuidos de importance economica en Chile y claves para su determinación. Sociedad Biologico Concepción, Publicación Especial 1:1–153.

Barbut, J. 2008. Révision du genre Rachiplusia Hampson, 1913 (Lepidoptera, Noctuidae, Plusiinae). Bulletin de la Société entomologique de France113(4):445–452.

Goater, B., L. Ronkay and M. Fibiger. 2003. Noctuidae Europaeae. Vol. 10, Catocalinae, Plusiinae. Entomological Press, Sorø, 452 pp.

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.

Copyright © Ted C. MacRae 2011

A Brazilian longhorned beetle – Oxymerus aculeatus

/ Ted C. MacRae / 9 Comments

Oxymerus aculeatus aculeatus | January 2011 | nr. Campinas, São Paulo, Brazil

I was going through photographs from my visit to Brazil this past January and came across this forgotten photo of a longhorned beetle taken near Campinas in São Paulo.  Although I didn’t recognize the genus immediately, I was rather sure it belonged to the great tribe Trachyderini, generally characterized by medium to large-sized, brightly colored, diurnal (active during the day) species.  Knowing this it didn’t take me long to identify the species as Oxymerus aculeatus, occurring from Nicaragua and the West Indies south to Bolivia and Uruguay and, thus, the most widely distributed of the ten species in this exclusively Neotropical genus. As is typical with such widespread species, a few subspecies have also been described—this one should be the nominate subspecies, widely distributed throughout central, eastern, and southeastern Brazil (Hingrid et al 2010).

Like most other members of the family Cerambycidae, O. aculeatus is presumed to utilize dead or dying wood for larval development, but little else is known regarding its habits and host plants. Members of the tribe are often found frequenting flowers, although this and a few other individuals were encountered resting on the underside of foliage on an unidentified tree. The Florida Department of Agriculture & Consumer Services has become concerned about the possible establishment of this species in the U.S. after two recent collections of the West Indian subspecies in south Florida (Thomas 2006). Whether it goes on to have any economic impact remains to be seen, but if recent history with other wood boring beetles is any indication (e.g., Asian longhorned beetle, Anoplophora glabripennis; emerald ash borer, Agrilus planipennis; etc.) the concern may be warranted.

REFERENCE:

Hingrid Y. S. Q., J. P. Botero R. and M. L. Monné. 2010. Insecta, Coleoptera, Cerambycidae, Cerambycinae, Trachyderini: New state and country records from South America. Checklist 6(3):364–376.

Thomas, M. C. 2006. Another Neotropical longhorn beetle (Coleoptera: Cerambycidae) apparently new to the mainland of Florida. UF/IFAS Pest Alert (website accessed 7 Nov 2011).

Copyright © Ted C. MacRae 2011

Cicindela albissima—The Coral Pink Sand Dunes Tiger Beetle

/ Ted C. MacRae / 17 Comments

Coral Pink Sand Dunes State Park, Utah

The week had started off good, with three species of western sand dune endemic tiger beetles (Cicindela formosa gibsoni, C. scutellaris yampae, and C. arenicola) and a variety of sometimes spectacular Crossidius longhorned beeltes having been encountered.  Mid-week, however, had brought a lull in our success—the long drive to southwestern Idaho was not rewarded with finding C. waynei, endemic only to Bruneau Sand Dunes State Park, and an even longer drive was required to backtrack and then drop down to the southwestern corner of Utah in hopes of finding the equally rare and restricted C. albissima.  Had it not been for our continued success with different species and subspecies of Crossidius longhorns the drive might have felt like a lesson in futility.  Still, on a collecting trip a new day and new locality brings new hope, and anticipation grew as we passed through lodgepole pine forests on stunning black lava fields and wind-carved red sandstones on the final approach to Coral Pink Sand Dunes State Park.

Colored pink by iron oxide minerals, the dunes are estimated at 10,000 to 15,000 years old.

Words cannot describe the stunningly spectacular landscape that unfolded before us as we entered the park.  The scenery alone makes Coral Pink Sand Dunes worthy, in my humble opinion, of National Park status, but it is C. albissima—occurring only on the park’s vivid pink dunes and nowhere else in the world—that makes this place truly special.  Precisely where in the park the beetle lives is a matter of public record, as Chris Wirth (author of the intermittent but highly focused blog Cicindela) and Randolph-Macon College Professor Emeritus Barry Knisley have produced a wonderfully detailed and well illustrated brochure about the beetle and its life history, population trends, and limiting factors.  What remained to be determined was whether the beetles would be active during the brief window of time available to look for it.  Cicindela albissima is a so-called “spring-fall” species in reference to the bimodal adult activity period, but activity in the fall is much less predictable than in the spring depending on moisture availability.  The day was perfect—temperatures in the 70s by mid-morning, only a light breeze, and a sharp, blue, cloudless sky.  All we could do was look.

Adult beetles were found on the northern edge of this dune. A majority were seen amongst sparse vegetation rather than barren areas.

It didn’t take long really to find them, as the adults were already out in encouragingly strong numbers. Of the several dozen adults we saw, all but one were seen atop the northern edge of one particular sparsely vegetated dune.  I suspect the larval burrows were at the bottom of the steep northern dune escarpment in the more stable wind-scoured sandstone clays that lay between individual dunes.  Vivid white and floating across the sand on long delicate legs, the elegance of their beauty was a stark contrast to the harshness of the surrounding landscape.  With a miniscule range of only 400 hectares, C. albissima is one of North America’s rarest tiger beetles, and I felt truly priviledged to join the small ranks of those who have seen this beetle alive in its native habitat and could appreciate the significance of the event.  Of course, the sense of accomplishment would not be complete unless I also succeeded in photographing the species in the field, and although the adults were quite wary and active, I was happy with several of the photos that I ended up with.  Similar to what I observed with C. arenicola, adults amongst the vegetation seemed slightly less skittish than those out in the open, so it was in the vegetated areas that I concentrated my efforts.  My only regret was not adding extension tubes to allow some real closeup portraiture, but the beetles seemed far too wary to have put up with the decrease in working distance that would have entailed.  At any rate, here are some of my favorites:




What the future holds for C. albissima remains unclear.  Designation of the beetle’s home range as a preserve (albeit tiny) would seem to offer long term protection, but a  large portion of this area is open to off-road vehicular traffic (although not a single one was seen during the time that we were there).  An even greater threat exists in the potential for extended drought affecting the entire population, and as greenhouse gases continue to accumulate in the atmosphere the chance of impacts from unusual weather events only grows. I feel lucky to be among the few that have witnessed this beautiful species in nature, but I sincerely hope I am not among the last.

ORV tracks can be seen just outside the conservation area boundary

Copyright © Ted C. MacRae 2011

Isn’t she splendid?!

/ Ted C. MacRae / 15 Comments

Cicindela splendida | Bald Hill Glade Natural Area, Ripley Co., Missouri

This gorgeous female Cicindela splendida emerged recently from one of my rearing containers.  She was one of several 3rd instar larvae that I collected this past June from their burrows in a dolomite glade in southeastern Missouri.  I had suspected they might represent this species because of the bright, metallic sheen on their heads and decided to rear them out to find out for sure.  Rearing tiger beetles is fun and easy—all you have to do is fill a container with native soil, make a “starter” burrow¹ and drop them in. In this case, I also partially sunk a native rock into the soil in the center of the container, something I have started doing recently as it gives the emerged adult an elevated and more visually appealing surface on which to perch than the soil should I desire to take photographs.

¹ Larvae will dig new burrows on their own, but starter burrows allow you to place the burrow where you want it.  They are essential if more than one larva is introduced to the container, as wandering larvae will fight when they encounter each other. I like to start the burrow in a corner of the container (a pencil works great for this) and push down to the bottom of the container so I can see into the burrow from outside to monitor the larva as it develops.  After introducing the larva to its burrow, I push the soil around the entrance to seal it lightly to keep the larva from immediately crawling back out.  The larva will eventually reopen the burrow but generally accepts it, digging it out further to its liking and shaping the entrance to precisely fit the size and shape of its head.

Reared from 3rd instar larva, burrow in sparsely vegetated clay exposure of dolomite glade.

With tiger beetle rearing, feeding time is fun time! Our lab rears insects for testing in abundance, and there are always leftovers. Really just about any insect that can be pulled into the burrow will be acceptable as prey, but lepidopteran caterpillars are my favorite. I use mostly early instar tobacco hornworm larvae, choosing the size as appropriate for the size of the tiger beetle larva—the big ones (e.g. 3rd instar Tetracha) can handle caterpillars 35-40 mm in length and 6-8 mm in diameter, while neonates must be used for the smallest ones (e.g. 1st instar Cylindera celeripes and C. cursitans). I find it endlessly entertaining to sneak up on the larva sitting at the entrance of its burrow, slowly position a caterpillar above the burrow entrance with forceps, and dangle it to entice the tiger beetle larva to lurch out, grab the caterpillar, and drag it down into its burrow—all in a split second! If the larva drops down from the burrow entrance during my approach I just drop the caterpillar into the burrow (though this isn’t nearly as much fun).

Copyright © Ted C. MacRae 2011

St. Anthony Dune Tiger Beetle

/ Ted C. MacRae / 17 Comments

Sand dune habitat for Cicindela arenicola | vic. Idaho Falls, Idaho

After kicking off the 2011 fall tiger beetle trip by finding Cicindela formosa gibsoni and C. scutellaris yampae in the Yampa Valley sand dunes in northwestern Colorado, I was even more optimistic about my chances of seeing the main goals of the trip—the four C. maritima species group endemics that inhabit sand dunes in Idaho (St. Anthony Dune Tiger Beetle—C. arenicola, and Bruneau Dune Tiger Beetle—C. waynei), Utah (Coral Pink Sand Dune Tiger Beetle—C. albissima), and Colorado (Colorado Dune Tiger Beetle—C. theatina).  Each of these closely related species is restricted to a single sand dune system in their respective states, resulting in small populations that are especially vulnerable to drought and threats to their required habitats (primarily invasive plants and offroad recreational vehicles).  Cicindela arenicola, described from the St. Anthony Dune system of southeastern Idaho (Rumpp 1967) was our first target, and while the drive through the Snake River Valley—aspen and maple in blazing full color—was stunningly beautiful, all I could think about during the 6-hour drive was the rising temperatures outside and the tendency of these sand dune tiger beetles to dig in if it gets too hot.  I had information about several localities along the St. Anthony Dune system, and by the time we arrived at the first of these it was already early afternoon.

Cicindela arenicola adult burrows

Walking onto the dunes at a locality near Idaho Falls, it didn’t take long to find the unmistakable signature of adult activity—burrows.  Many insects (especially bees) and even non-insects (spiders, solifugids, etc.) that live on sand dunes create burrows that can look similar to those created by adult tiger beetles.  However, after years of experience I can almost tell at a glance whether a burrow has been created by a tiger beetle versus some other arthropod by the size and shape of the opening and appearance of the diggings.  When there is doubt, a little bit of excavating with a knife gives further clues in the shape of the tunnel—flatter than most other diggers and angling almost horizontally back into the sand before taking a dive a few inches back.  Wind quickly obliterates evidence of the burrow entrance and pile of diggings, so when these are present and fresh-looking the beetles have either just dug in or just dug out.  I excavated a number of burrows that turned out to be empty, suggesting the beetles were out and about if only I could find them.  And find them I did, mostly along the sloping, south-facing dune face above the flatter sand plain below.  They were as beautiful as I imagined they would be—bold, white markings, screaming green and copper highlights on the head and pronotum, and a dense covering of white hairs on the sides and undersurface.  They were also extremely active and wary, so much so that I didn’t even attempt to photograph them for the time being despite the decent number of individuals that we saw at the site.

Cicindela arenicola adult excavating burrow (click for better view of beetle just inside burrow entrance)

Cicindela arenicola in completed adult burrow | September 2011 | Idaho Falls, Idaho

There were other nearby sites that I had planned to check also, but with good numbers seen already and several other interesting insects (e.g., Crossidius spp.) found in abundance on the blooms of snakeweed plants growing on the backside of the dunes, there was really no reason to go anywhere else.  Besides, I still had not even attempted a field photograph of C. arenicola (although I had made sure to capture some live adults for studio shots that night as a backup).  As the sun began sinking in the western sky and temperatures began to cool off, I noticed the adults were becoming scarce and that fresh burrows were appearing on the dune surface.  In contrast to earlier in the day, adult beetles were found in nearly every burrow that I excavated—the beetles were digging in, and if I wanted field photographs it was now or never.  I managed a few distant shots of the first several adults I tried to stalk, but none of these were close to keepers.  I eventually noticed that beetles in the sparsely vegetated areas of the dune seemed to be slightly more approachable than those out on the open dune surface (perhaps they felt a little more secure in the presence of some cover), and although the vegetation often obscured clear views of the beetles, it was at least a more manageable problem than not even being able to approach them.  Finally, after considerable effort, I managed the photograph shown below.  I’d like to take credit for the near perfect composition and focus, but it was an actually a completely accidental shot.  I had been stalking the beetle for some time and had finally gotten closer to it than I had managed for any other beetle.  Rather than a presenting me with a lateral profile, the beetle was directly facing me as I closed in for the shot. Just as I pressed the shutter the beetle turned profile and then darted off.  Other than nipping the middle tarsus I don’t think I could’ve framed this uncropped photo better if I had tried.

Cicindela arenicola | September 2011 | vic. Idaho Falls, Idaho

Cicindela arenicola is closely related to C. waynei (known only from sand dunes in and around Bruneau Dunes State Park in southwestern Idaho), and it is only recently that the two have been considered separate species.  Cicindela waynei differs in its generally green rather than bronze coloration, more expanded white markings, and the presence of a curious upward projecting tooth on the male mandible (Pearson et al. 2006).  There are some populations in south-central Idaho assigned to C. arenicola that show an intergradation of characters between the two species, primarily in the presence of individuals with green coloration and expanded markings, so I found it interesting to encounter just such an individual at this southeastern Idaho site as well.  The individual, a male (and photographed in a terrarium that evening), looks very much like C. waynei except that it lacks the distinctive mandibular tooth characteristic of that species.

Male from same locality with green elytra and expanded markings

Cicindela arenicola is largely restricted to the Snake River Plain of southern Idaho, with a small population also occurring in the Centennial Sandhills of southwestern Montana (Winton et al. 2010). The sand dunes on which these beetles depend have suffered numerous assaults in recent years at the hands of man, with exotic invasives (Bouffard et al. 2009), trampling by cattle (Bauer 1991), and offroad vehicular traffic having the greatest impact on tiger beetle populations.  The species has been considered for listing on the Endangered Species List due to the imperiled nature of its limited habitat, but to this point such status has not yet been accorded.  It has, however, been listed as globally imperiled by the Idaho Department of Fish and Game and the Bureau of Land Management.  Most people are completely unaware that this beetle exists, and probably fewer still would even care.  For me personally, however, the chance to see this rare and beautiful beetle in its native habitat and spend time watching its behavior was a thrill I won’t soon forget.

Tiger beetle's-eye view of its preferred sand dune habitat.

I haven’t forgotten about the challenges that led to this post.  However, the hour is late and I need my rest.  Points will be awarded over the next day or so, and the winner of BitB Challenge Session #4 will be crowned!  In the meantime, I’ve released the submitted comments so you can see how your answers fared against the competition—no do-overs!

REFERENCES:

Bauer, K. L. 1991. Observations on the developmental biology of Cicindela arenicola Rumpp (Coleoptera: Cicindelidae). Great Basin Naturalist 51:226–235.

Bouffard, S. H., K. V. Tindall and K. Fothergill. 2009. Herbicide treatment to restore St. Anthony tiger beetle habitat: a pilot study. Cicindela 41(1):13–24.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States & Canada: Identification, Natural History, and Distribution of the Cicindelidae. Oxford University Press, New York, NY. 227 pp.

Rumpp, N. L. 1967. A new species of Cicindela from Idaho (Coleoptera: Cicindelidae). Proceedings of the California Academy of Science 35:129–140.

Winton, R. C., M. G. Kippenhan and M. A. Ivie.  2010.  New state record for Cicindela arenicola Rumpp (Coleoptera: Carabidae: Cicindelinae) in southwestern Montana.  The Coleopterists Bulletin 64(1):43–44.

Copyright © Ted C. MacRae 2011

Lytta vulnerata cooperi

/ Ted C. MacRae / 7 Comments

Lytta vulnerata cooperi | Idaho Falls, Idaho

I had other quarry on my mind when I visited Idaho a couple of weeks ago, but I couldn’t help but pay attention to this blister beetle (family Meloidae) feeding on rabbit brush flowers for the following two reasons: 1) its spectacular and boldly contrasting black and orange coloration, and 2) my collecting partner, Jeff Huether, is an expert on North American Meloidae. My identification of this individual as Lytta vulnerata is based strictly on one line of evidence: Jeff said that’s what it is!  My further identification as the subspecies L. vulnerata cooperi is more tenuous, being based on the distinctly sculptured elytra, immaculate pronotum, and more northerly location (nominotypical individuals, at least from what I can tell looking at photos assigned to the two subspecies, have the elytra indistinctly sculptured, generally exhibit a median line or vitta on the pronotum, and occur further south).

Note distinct elytral sculpturing and immaculate pronotum

Copyright © Ted C. MacRae 2011