A chalcidid jewel beetle parasitoid wasp

Acanthochalcis nigricans | Gloss Mountains State Park, Major Co., Oklahoma

Acanthochalcis nigricans | Gloss Mountains State Park, Major Co., Oklahoma

As a student of jewel beetles with an interest in their larval host plant associations, rearing has been an important tool for my studies. Through the years, I’ve retrieved literally hundreds of batches of dead wood from the field and placed them in rearing containers that I keep in my garage. It’s hard work, but the several thousand jewel beetles that I’ve reared from these batches, many representing new distributions, host associations, and even new species (e.g., MacRae 2003) clearly suggest it has been worth the effort. Of course, jewel beetles are not the only insects that emerge from this wood. Numerous other insects have shown up in the rearing containers as well, mostly beetles in other families associated with dead wood such as longhorned beetles, powderpost beetles, checkered beetles, etc. Non-beetles have been reared as well, mostly representing parasitic hymenopterans, and in this group my favorite are the chalcidid wasps (family Chalcididae). Chalcidids and some of their close relatives are instantly recognizable by their greatly swollen and toothed hind femora. Most species in this family are parasitoids of Lepidoptera and Diptera, but some parasitize other insects, including jewel beetles and especially those in the genus Chrysobothris. I have reared a few hundred of these wasps over the years, representing at least a dozen or more species and currently being identified by fellow buprestophile Henry Hespenheide. Once identified, it will be an easy matter to associate these specimens with the Chrysobothris beetles that emerged with them from the same batch of wood. From this, we anticipate that any number of new parasitic wasp/beetle host associations will be revealed.

Among chalcidid wasps, the large size and very long ovipositor distinguish this genus.

Among chalcidid wasps, the large size and very long ovipositor distinguish this genus.

The chalcidid wasp featured in this post was not reared, but rather was encountered in the field during my recent collecting trip to northwestern Oklahoma. In fact, it was the very first insect that I encountered at the very first site that I stopped at—Gloss Mountains State Park. Although the wasp was photographed on a dead branch of eastern red-cedar (Juniperus virginiana), I first saw it on a dead branch of mesquite (Prosopis glandulosa). Based on its long ovipositor and large size (~19 mm in length, including the ovipositor), I presume this to be one of the two Acanthochalcis species commonly encountered in North America, with the presence of white pubescent patches on its abdomen identifying it as A. nigricans, occurring across the southwestern U.S. from Kansas and Oklahoma to California (A. unispinosa, ranging from Texas to California, lacks these pubescent patches). This species is a known associate of Chrysobothris jewel beetles, including C. femorata and C. edwardsii (Universal Chalcidoidea Database), but in this case I believe it is associated with C. octocola—an equally large jewel beetle that I first encountered on the mesquite at this very spot last fall (a new state record!). I beat quite a few more C. octocola adults from dead mesquite branches during this trip but didn’t find any other Chrysobothris spp. associated with the mesquite. That said, it is possible that the wasp is associated with the larger of two species of Chrysobothris that I beat from the eastern red-cedar at the site (forgive me for being coy about the identity of the beetle right now, as it will be the subject of a future post). However, since all of the wasps I saw that day were originally seen on or flying around dead mesquite branches I’m betting on C. octocola.

The white abdominal pubescent patches distinguish this species from A. unispinosa.

The white abdominal pubescent patches distinguish this species from A. unispinosa.

REFERENCE:

MacRae, T. C. 2003. Agrilus (s. str.) betulanigrae MacRae (Coleoptera: Buprestidae: Agrilini), a new species from North America, with comments on subgeneric placement and a key to the otiosus species-group in North America. Zootaxa 380:1–9.

Copyright © Ted C. MacRae 2013

Cosmetid harvestman with parasitic/phoretic mites in Argentina

Metalibitia sp. poss. paraguayensis | Corrientes Province, Argentina

While searching logpiles last month in a relatively intact tract “Selva Paranaense” near Paso de la Patria (Corrientes Prov., Argentina), the most interesting find for me was , a bizarre longhorned beetle that is either amazingly cryptic or a curious mimic (I couldn’t decide). There wasn’t much else to be seen in the logpiles—it had been a very dry summer in northern Argentina, but I did find this interesting species of harvestman (class Arachnida, order Opiliones) huddled together in one of the punkier piles of wood.

Knowing little about harvestman taxonomy (but knowing of several specialists who do), I sent the photos around for expert opinion. Everyone responded with the same opinion—family Cosmetidae, apparently distinguished by its spoon-shaped pedipalps. Marshal Hedin compared them to this similar-looking species photographed in Bolivia, Christopher Taylor (Catalogue of Organisms) thought they might be a species of Metalibitia and Ricardo Pinto-da-Rocha suggested M. paraguayensis as having been recorded from the province of Corrientes (although a specimen would need to be examined to confirm the identification). My thanks to each of these gentlemen for weighing in on a possible ID.

Argentina represents the southernmost extent of this strictly New World family of harvestmen, while to the north the family extends up to the southern U.S. (genus Vonones). In between, the family is diverse and comprises up to one-third to one-half of the harvestman fauna (Kury & Pinto-da-Rocha 2007). Many species in the family are ornately marked, giving rise to the family name which is derived from the Greek kosmetós (= ornate)—check out this gallery of photos at Flickr to see some truly spectacular examples.

While I was photographing these individuals, and even when I first began processing the photos, I thought that they were quite dirty and debated whether to clean them in PhotoShop. Then I realized that the numerous white spots were not debris, but mites! Whether these represent a parasitic or phoretic relationship is not clear to me, however, and none of the gentlemen I sent the photos to offered any comment about them. Erythraeid and thrombidiid mites are well documented as harvestman ectoparasites during their larval stage, with recorded hosts including Neotropical species of Cosmetidae (Townsend et al. 2008). The tiny, white mites on these individuals, however, do not resemble the large, red erythraeid mites (probably genus Leptus) that I have seen parasitizing our North American harvestman species, and their numbers on multiple individuals is, to me, more indicative of a phoretic relationship. If you want to become thoroughly confused by the tremendous diversity of mites the parasitize harvestmen, see the comprehensive review by Cokendolpher (1993).

REFERENCES:

Cokendolpher, J. C. 1993. Pathogens and parasites of Opiliones (Arthropoda: Arachnida). The Journal of Arachnology 21:120–146.

Townsend, V. R., D. N. Proud, M. K. Moore, J. A. Tibbetts, J. A. Burns, R. K. Hunter, S. R Lazarowitz & B. E. Felgenhauer. 2008. Parasitic and phoretic mites associated with Neotropical harvestmen from Trinidad, West Indies. Annals of the Entomological Society of America 101(6):1026–1032.

Kury, A. B. & R. Pinto-da-Rocha. 2007. Cosmetidae Koch, 1839. Pp 182–185. In: R. Pinto-da-Rocha, G. Machado & G. Giribet (Eds.). Harvestmen: The Biology of the Opiliones. Harvard University Press, Cambridge and London, x + 597 pp.

Copyright © Ted C. MacRae 2012

Of Bots and Warbles

As an undergraduate at Truman State University during the mid-90’s I was part of a small mammal research group led by Dr. Scott Ellis.  My focus was on flying squirrels, but others in the group studied mice.  There were always opportunities to help my colleagues trap mice, and that is where I first encountered bot flies (Oestridae: Cuterebra spp.).  It was common for the live trapped mice to be infected with bot fly larvae, or bots, developing just under the skin of the host.  You might expect a fly parasite of a mouse to be relatively small but that is not the case with bot flies.  The bots cause a grotesquely large growth (or warble), and Cramer and Cameron (2006) report that a single bot can weigh as much as 5% of the host body weight.  That’s like a 150 lb guy having a 7.5 lb growth!  One unfortunate mouse that comes to mind had a warble on its head which caused its eye to bulge out.  I hate to make light of that poor mouse’s condition, but I distinctly recall that the bulging eye made it look as if it was continually surprised.  That said, Cuterebra fontinella infections are not thought to have a negative impact on white-footed mice, and in fact some studies have found that infected mice actually live longer than their non-infected neighbors (Cramer and Cameron 2006).  This relatively benign relationship between host and parasite is also the case in general with other species of Cuterebra, which is attributed to the long evolutionary history shared between the parasite and a single or very few closely related hosts (Catts 1982).  Negative impact or not, I was glad that I didn’t have to worry about bot flies infecting me, at least while I was in temperate Missouri.  Of course I had heard plenty of stories of humans being parasitized in the tropics by the human-attacking Dermatobia hominis, and they didn’t sound like very pleasant experiences.  My favorite story involved the person that had a bot in their ear that just about drove them crazy because they could hear the bot any time it changed positions.  Actually the Slansky article discusses the more negative interaction between D. hominis and its host, and this has been attributed to the less specialized relationship between the parasite and any one host because D. hominis has a broad range of hosts. 

Dermatobia hominis actually employ another insect to deliver its eggs to the host!  They lay eggs on mosquitoes or other blood-feeding Diptera for subsequent transfer to the host.  This makes a lot of sense from my point of view as a potential host—the adults are huge (bumble bee size), and I sure would be wary of one approaching me.  But mosquitoes, now there’s an idea—they are very adept at finding their hosts and are inconspicuous enough that they just might be able to get in close enough to allow the body heat of the host to stimulate the hatching and deposition of a bot.

There are other species of Cuterebra, and each is host specific to some degree.  Cuterebra abdominalis (Fig. 1) and Cuterebra buccata are both specific to lagomorphs (rabbits).  No doubt male tree squirrels and chipmunks get a little nervous every time they hear the species name of their bot fly—“emasculator”.  The species name originated from the observation that the warbles were often located near the genitalia of the squirrels, which prompted the idea, given the impressive size of the warble, that there must be an impact on the reproductive ability of the afflicted squirrels.  Luckily for the squirrels, research has demonstrated that the species name is a misnomer (Catts 1982).

Figure 1. Cuterebra abdominalis, a rabbit bot fly

I knew nothing of the adult Cuterebra at the time I saw the parasitized mice, but that changed when Ted MacRae netted an adult rabbit bot fly, Cuterebra buccata, while we were looking for tiger beetles in northeastern Missouri.  In May of 2006, my wife Jess and I came across an adult C. abdominalis on the edge of a glade at Shaw Nature Reserve near St. Louis, and it is this photo that I discuss more below (Fig. 1).  The only other encounter was from southeastern Missouri in April of 2009 when Ted again found a rabbit bot fly, and this individual had only recently emerged from its puparium (Figs. 2 and 3– See Ted MacRae’s previous post from 2009 on this exact same fly).  All told, that’s only three encounters with adult bot flies from countless hours spent in the field, so my experience is that adult bot flies are rarely encountered.

Figure 2. Newly emerged rabbit bot fly, Cuterebra buccata

Figure 3. Newly emerged C. buccata with shed puparium



The image in Figure 1 represents well the type of photographic opportunity that I look for because it readily leads into various side stories.  Here are some examples: 

1) Amazing natural history—you just can’t make this stuff up.  The Catts review article cited discusses numerous other aspects of bot fly natural history in addition to the discussion above.  For example:

  1. Cuterebra spp. are thought to oviposit in the host habitat where the eggs await close passage of a host.  As with the D. hominis, the body heat of the host stimulates the eggs to hatch. The first instar larvae enter the host through an existing orifice or wound and then travel through the host to find a suitable subcutaneous location to create a warble.  Here, the larva molts to the second instar and continues to draw nourishment from the host.  Cuterebra larvae feed on fluids of the host as opposed to feeding on actual tissue, which would be more damaging to the host.
  2. The larvae spend roughly one month in the host.  Upon completion of the third instar, the larva exits the host, digs into the soil, and pupates.  Bot flies overwinter as pupae.
  3. Adults do not feed and are relatively short-lived.  Their attention is focused on the serious business of reproduction. 

2) Mimicry.  As you can see from the image, C. abdominalis very much resembles a bumble bee.  This image is great for presentations because it captures the attention of grade school kids.  I include this image at the end of a series of slides containing images of bees and wasps alongside the flies that mimic them.  Kids become very engaged and have a lot of fun trying to guess which images represent the models and which represent the mimics.  By the end of the series the kids have become pretty savvy about picking out the imposters but I present this image last and C. abdominalis is so bizarre that it always stumps the audience.  The kids become even more captivated by the discussion of how bot flies make a living.

3) Insect photography technique.  It’s thrilling to find new insects, but the experience can quickly turn disappointing if the insect flies off never to be seen again just as you begin to approach it for a photograph. That would have been the case with my encounter with C. abdominalis if I didn’t have a companion with me in the field.  I was lucky to have my wife, Jess, with me on this hike.  She kept an eye on the fly as I moved in for pictures.  Once or twice it flew at my approach, and Jess was able to keep track of it so I could try again.  Ted and I have also acted as spotters for one another, and this has made the difference between getting the pic or not.

4) Great location.  We encountered C. abdominalis on the edge of the scenic glade that slopes away from the Trail House at Shaw Nature Reserve in Franklin County, Missouri.  It’s always fun to revisit certain places and get to know them and the photographic opportunities they provide.  The Nature Reserve is one such place for me.  It offers countless opportunities for insect photography close to St. Louis due to a wide variety of habitats including prairie, glade, forest, wetland, and riparian areas. 

REFERENCES:

Catts E. 1982. Biology of New World bot flies: Cuterebridae. Annual Review of Entomology 27:313–338.

Cramer J. and G. Cameron. 2006. Effects of bot fly (Cuterebra fontinella) parasitism on a population of white-footed mice (Peromyscus leucopus). Journal of Mammalogy 86:1103–1111.

Slansky, F. 2007. Insect/mammal associations: Effects of cuterebrid bot fly parasites on their hosts. Annual Review of Entomology 52:17–36.

Copyright © Christopher R. Brown 2012

The Methocha

As pointed out in my recent post, , there is much to learn still regarding tiger beetle larval parasitoids. In addition to bee flies (order Diptera, family Bombyliidae) of the genus Anthrax, tiphiid wasps (order Hymenoptera, family Tiphiidae) in the genus Methocha also parasitize tiger beetles in their larval burrows. Unlike bee flies, however, which sneakily lay their eggs in and around tiger beetle burrows when their victim isn’t watching, Methocha females aggressively engage the larva and even allow themselves to be grasped within the beetle larva’s sickle-shaped mandibles in order to gain entry to the beetle’s burrow.

Methocha appears to be a rather diverse genus, but it’s taxonomy is still incompletely known. George Waldren from Dallas, Texas is working on a revision of the genus and has found several new species in Texas alone. George is interested in seeing Methocha material from other areas as well and recently sent me the following reminder that adult females are active now:

…if you know of any areas with many tiger beetle larvae, now is the time to find Methocha. They superficially look like Pseudomyrmex ants, but once you see one you’ll catch on to them quickly. I collected more than 70 females today in a large aggregation of Tetracha carolina burrows.

In a subsequent message he adds:

Collect as many as you can, since they seem to be highly seasonal and rare most of the year. I almost always find them around beetle populations in sandy creek beds and receding bodies of water. A pooter works best if they are abundant and there isn’t much for them to hide under. Using your fingers also works—the sting is mild and usually doesn’t pierce the skin (depends on the person and size of the wasp). Vial collecting one by one works just as well.

Methocha females are generally overlooked due to their specialized life history and few specimens are in collections. Males are better represented since they’re easily collected with malaise traps.

If you have any Methocha specimens or manage to collect some, please contact George (contact info can be found at his BugGuide page). BugGuide does have a few photographs of these wasps to give you an idea of what they look like, but this excellent video titled “The Methocha” from Life in the Undergrowth with David Attenborough provides an unparalleled look at their appearance and behavior:


Copyright © Ted C. MacRae 2011

Bee Fly Parasitism of Tetracha virginica

I expected to gain a better understanding of insect photography principles and techniques at last weekend’s BugShot insect photography workshop at Shaw Nature Reserve in Gray Summit, Missouri.  I even expected that I would walk away from the event with some new friends.  The one thing I did not expect was the discovery of an apparently unreported host/parasitoid relationship amongst my beloved tiger beetles.  Nevertheless, that’s exactly what happened in a patch of barren soil just outside of the Dana Brown Education Center where the event was being held.

Tetracha virginica 3rd instar larva | Shaw Nature Reserve, Franklin Co., Missouri

I had spied the small cluster of tiger beetle burrows the previous day as we left on our first group hike.  The burrows were unmistakably those of Tetracha virginica (Virginia metallic tiger beetle) due to their size (no other tiger beetle in east-central Missouri approaches the size of this species), and in fact some of the larvae were seen sitting at the tops of their burrows.  Tetracha larvae are easily distinguished from other genera of North American tiger beetles (in addition to their size) by their distinctive white-margined pronotum.  I had to catch back up with the group but came back later in the day and took a few photographs of one of the larvae sitting in its burrow.  Some of the other BugShot attendees were there and wanted to take photographs, but the larvae dropped on their less-practiced approach.  No problem, I just “fished” a larva out of its burrow and let them take their photographs.  When they finished, I began taking my own photographs, but I only got off one shot before the larva suddenly made a bee-line for its burrow and dropped in before I could block its escape.  Oh well, I do already have photographs of the larva of this species from other locations.

Tetracha virginica 3rd instar larva | Shaw Nature Reserve, Franklin Co., Missouri

The next day I passed by the burrows again with Crystal and Lee.  I really wanted them to see the larvae, but they were not active.  No problem, I grabbed a long grass stem, chewed on one end, and inserted it to a depth of about 35 cm before it hit bottom.  A little jiggling to get the larva to bite, then a quick jerk back and out came the larva.  I never tire of seeing someone witness this for the first time—the way they jump back half-startled when they see the otherworldly larva flying through the air and landing on the grass.  I grabbed the larva and placed it on the barren clay to let them take photographs.  Crystal went first, and as she looked at the larva through her viewfinder she exclaimed, “there are wormy-things [the technical term, of course] on him.”  Lee and I looked, and sure enough there were two small “wormy-things” attached to the back of the tiger beetle.  I immediately recognized them as bee fly larvae (family Bombyliidae)—specifically Anthrax analis, the only bee fly known to parasitize tiger beetle larvae in the United States.  I was quite excited by this discovery, as I have never seen these before despite fishing untold numbers of tiger beetle larvae from their burrows over the past decade or so.  We all went camera crazy and took our turns photographing larvae and host, after which I popped it into a vial to keep for an attempt at rearing out the bee flies.

Anthrax analis larvae attached to abdomen of Tetracha virginica larva

It now seems that our find represents more than just a personal discovery, as bee flies—to my knowledge—have not yet been reported parasitizing any species of the genus Tetracha.  Of the 70 Anthrax spp. for which hosts have been recorded (Yeates and Greathead 1997), only three are known to parasitize tiger beetles.  Shelford (1913) gave the first account of A. analis (as Spogostylum anale) parasitzing Cicindela scutellaris lecontei, noting that the adult females lay their eggs by flying backward and downward while thrusting the abdomen forward until it touches the sand near the host burrow entrance.  Hamilton (1925) found Cicindelidia obsoleta parasitized by this species, and Bram and Knisley (1982) expanded its known host spectrum to include C. hirticollis, C. tranquebarica, Cicindelidia punctulata, and Ellipsoptera marginata.  Photographs of larvae (presumably of this species) parasitizing undetermined tiger beetle larvae can be seen in Pearson and Vogler (2001) and in this photo by Chris Wirth.  Anthrax gideon has been recorded parasitizing Pseudoxycheila tarsalis in Costa Rica (Palmer 1982) and Oxycheila trisis in Brazil (Arndt and Costa 2001), while a third undetermined Anthrax sp. has been reared from larvae of Pentacomia ventralis, also in Brazil (Arndt and Costa 2001).  Oxycheila and Pseudoxycheila are related to Tetracha at the tribal/subtribal level (depending on which classification you follow), so the finding of A. analis utilizing Tetracha is not unexpected.

Closer view of anteriormost Anthrax analis larva

The beetle larva and its unwelcome tagalongs is now in a container of native soil and has accepted the starter burrow that I made for it. Hopefully at least one of the bee fly larvae will complete its development and emerge as an adult to allow confirmation of its identity.  If this host association does turn out to be unreported, we will follow up with at least a short journal communication.  To that end, any literature citations you are aware of regarding bee fly parasitism of tiger beetles that is not listed below would be most welcome.

Congratulations to Ben Coulter, who wins yet another BitB Challenge with 14 points (this guy is a machine!), and Mr. Phidippus came close with 13 points.  Ben and Phiddy were the only participants that figured out the parasites were bee flies of the genus Anthrax, and Phiddy was the only participant to guess the correct genus for the host.  Ben’s win gives him a now commanding lead with 49 points in the current BitB Challenge Session #4 as we enter the home stretch.  Mr. Phidippus and Roy are still in striking distance with 39 and 28 points, respectively.  Is anybody capable of keeping him from his third title?  We shall see.

REFERENCES:

Arndt, E. and C. Costa.  2001.  Parasitism of Neotropical tiger beetles (Coleoptera: Carabidae: Cicindelinae) by Anthrax (Diptera: Bombyliidae).  Studies on Neotropical Fauna and Environment 36(1):63–66.

Bram, A. L. and C. B. Knisley.  1982.  Studies on the bee fly Anthrax analis (Bombyliidae), parasitic on tiger beetle larvae (Cicindelidae).  Virginia Journal of Science 33:90.

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 (Art. 17):1–87.

Palmer, M. K.  1982.  Biology and behavior of two species of Anthrax (Diptera: Bombyliidae), parasitoids of the larvae of tiger beetles (Coleoptera: Cicindelidae).  Annals of the Entomological Society of America 75(1):61–70.

Pearson, D. L. and A. P. Vogler.  2001. Tiger Beetles: The Evolution, Ecology, and Diversity of the Cicindelids.  Cornell University Press, Ithaca, New York, 333 pp.

Shelford, V. E.  1913.  The life history of a bee-fly (Spogostylum anale Say) parasite of the larva of a tiger beetle (Cicindela scutellaris Say var. lecontei Hald.).  Annals of the Entomological Society of America 6(2):213–225.

Yeates, D. K. and D. J. Greathead.  1997. The evolutionary pattern of host use in the Bombyliidae (Diptera): a diverse family of parasitoid flies.  Biological Journal of the  Linnaean Society 60:149—185.

Copyright © Ted C. MacRae 2011

Trichodes bibalteatus in Oklahoma

Among checkered beetles (family Cleridae), the genus Trichodes contains among the largest and most strikingly-colored species.  The 11 North American species of this predominantly Holarctic genus are primarily western in distribution, although two species (T. nuttalli and T. apivorus) do occur in the eastern U.S.  The individual in these photos was one of several I encountered feeding on the flowers of a yellow composite in the Gloss Mountains of northwestern Oklahoma during early July.  I take them to represent the species T. bibalteatus based on their close resemblance to the holotype of that species from the LeConte Collection in the Museum of Comparative Zoology at Harvard University.  While these photographs are admittedly far from perfect, they were about the best I could manage at the time considering the gusty post-storm winds that I encountered atop the mesa where these beetles were found (along with my continuing difficulty in achieving proper exposure with subjects on bright yellow flowers).

The striking colors of adult Trichodes and their frequent association with flowers for feeding and mating belies a more treacherous aspect of their life history.  While adults may serve as important pollinators of native plant species (Mawdsley 2004), they also lay their eggs on flowers.  The larvae that hatch from these eggs don’t eat the flower itself, but rather attach themselves to bees and wasps that visit the flower as they gather pollen for provisioning their own nests (Linsley & MacSwain 1943).  The larvae hitch a ride back to the hymenopteran’s nest, where they then prey on the developing brood and usurp pollen provisions for themselves.

Photo Details: Canon 50D w/ MP-E 65mm 1-5X macro lens (ISO 100, 1/250 sec, f/16), Canon MT-24EX flash (1/8 ratio) w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCE:

Linsley, E. G. & J. W. MacSwain. 1943. Observations on the life history of Trichodes ornatus (Coleoptera, Cleridae), a larval predator in the nests of bees and wasps. Annals of the Entomological Society of America 36:589–601.

Mawdsley, J. R. 2004. Pollen transport by North American Trichodes Herbst (Coleoptera: Cleridae). Proceedings of the Entomological Society of Washington 106(1):199-201.

Copyright © Ted C. MacRae 2010

Overlooked, needle-tailed, thick-headed fly

Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/16, MT-24EX flash 1/4 power w/ diffuser caps.

Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/16, MT-24EX flash 1/4 power w/ diffuser caps.

While photographing the rare Typocerus deceptus on flowers of wild hydrangea (Hydrangea arborescens) at Trail of Tears State Park in southeast Missouri last June, I encountered this strange fly also visiting the hydrangea blossoms.  At first I thought it was some weird type of syrphid fly, but it turns out to be a member of an even more unusual group of flies in the appropriately-named genus Stylogaster¹.  Although classified in the family Conopidae (thick-headed flies), members of this genus are placed in their own subfamily (Stylogastrinae) due to their unusual morphology and biology (obligate parasites of crickets, cockroaches and calyptrate flies).  Ninty-two described species are currently placed in the genus, only two of which occur in North America (the remainder are found chiefly in the Neotropics and in sub-Saharan Africa and southeast Asia).  This individual appears to be a female S. neglecta because of its short 2nd antennomere (antennal segment) and highly elongate 3rd antennomere (in S. biannulata, the 2nd antennomere is almost as long as the 3rd). Thus, the “overlooked, needle-tailed, thick-headed fly” – and who said common names are easier?

¹ Derived from the Latin stilus (needle) and the Greek γαστηρ (belly, stomach), a reference to the highly elongated female abdomen, or “tail.”

Morphologically, stylogastrines are distinguished from other conopids by their eggs, which feature a rigid barbed tip.  This, along with some behavioral observations, seems to imply a shooting oviposition technique; however, morphological evidence suggests that the eggs are forcibly jabbed into their hosts (Kotrba 1997).  The larvae hatch and develop inside their host as internal parasites, but other than the egg very little is known about the life histories of species in this genus (Couri and Pont 2006).  Adults are further distinguished by their long proboscis, which exceeds the length of the body when fully extended and is used to access nectar within a variety of flowers.  Adult females aggressively intercept hosts in-flight for oviposition, and speculation has been made that they are obligate associates of army ants (New World subfamily Ecitoninae and Old World subfamily Dorylinae), relying upon the ants’ raiding columns to flush out their prey.  However, since the genus also occurs in Madagascar and parts of Africa where army ants are completely absent, it is clear that at least some species of Stylogaster have no obligatory association with these ants (Stuckenberg 1963, Couri and Pont 2006).

REFERENCES:

Couri, M. S. and A. C. Pont. 2006. Eggs of Stylogaster Macquart (Diptera: Conopidae) on Madagascan Muscids (Diptera: Muscidae). Proceedings of the California Academy of Science 57(16):473-478.

Kotrba, M. 1997. Shoot or stab? Morphological evidence on the unresolved oviposition techique in Stylogaster Macquart (Diptera: Conopidae), including discussion of behavioral observations. Proceedings of the Entomological Society of Washington 99:613-621.

Stuckenberg, B. R.  1963.  A study on the biology of the genus Stylogaster, with the description of a new species from Madagascar.  Revue de Zoologie et Botaniques Africaines 68:251-275.

Copyright © Ted C. MacRae 2009

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Revisiting the Swift Tiger Beetle – Part 1

Photo details: Canon 100mm macro lens with 68mm extension on a Canon EOS 50D, ISO 100, 1/250 sec, f/13, MT-24EX flash 1/4 power through diffuser caps

Photo 1 - Cylindera celeripes at Alabaster Caverns State Park in northwestern Oklahoma.

When my hymenopterist friend, Mike Arduser, came back from his first trip to Oklahoma’s Four Canyon Preserve last September, my first thought upon seeing his photos of the area was, “Ooh, that looks like a good place for tiger beetles!” Its rugged red clay and gypsum exposures reminded me of similar country I had seen in the not-too-distant Gypsum Hills of south-central Kansas, where I was fortunate enough to observe a nice population of the fantastically beautiful Cicindela pulchra (beautiful tiger beetle) back in 2005. When I later realized that the area was only 30 miles southwest of a confirmed recent sighting of Cicindela celeripes (swift tiger beetle, now Cylindera celeripes), I thought, “Ooh, I wonder if celeripes might occur there also.”

Photo details: Canon 100mm macro lens with 68mm extension tube on a Canon EOS 50D, ISO 100, 1/250 sec, f/13, MT-24EX flash 1/4 power through diffuser caps

Photo 2 - Cylindera celeripes on lichen-encrusted clay soil at Alabaster Caverns State Park.

Recall that C. celeripes is one of North America’s rarest and least understood tiger beetles. This tiny, flightless, ant-like species has been recorded historically from eastern Nebraska south to north-central Texas, but its range appears to have become highly restricted over the past century. It hasn’t been seen in Nebraska for nearly 100 years now, and most recent records have come from its last known stronghold in the Flint Hills of Kansas. In 2003, however, a photographer by the name of Charles Schurch Lewallen posted on BugGuide a photograph of this species taken at Alabaster Caverns State Park in northwestern Oklahoma, and last year small numbers of adults were seen in the Loess Hills of western Iowa. This last sighting triggered an immediate trip to the site by myself and Chris Brown, who has been co-investigating the tiger beetle fauna of Missouri with me for several years now. The occurrence of this species in Iowa’s Loess Hills had reignited our hopes – faint as they were – that the beetle might yet occur in extreme northwestern Missouri, where the Loess Hills reach their southern terminus. We wanted to see the beetle in the wild to better understand its habitat requirements before resuming our search for this species in northwestern Missouri. We succeeded in finding the beetle – an amazing experience in itself – and brought three adults of this never-before-reared species back to the lab for photographs and an attempt at rearing. We did manage to obtain viable eggs, but we were not successful in rearing the larvae beyond first instar. I wrote about that experience last August in a post entitled, “The hunt for Cicindela celeripes” (that post is now currently in press as an article in the journal CICINDELA).

Photo details: Canon 100mm macro lens with 68mm extension tube on a Canon EOS 50D, ISO 100, 1/250 sec, f/11, MT-24EX flash 1/4 power through diffuser caps

Photo 3 - Cylindera celeripes on gypsum exposure at Alabaster Caverns State Park.

Thus, when my friend Mike asked me earlier this year if I might be interested in joining him on his return trip to Four Canyon Preserve in June, I jumped at the chance. I figured I could look for celeripes at the preserve, and if I failed to find it there then I would go to Alabaster Caverns and see if I could relocate the beetle where it had been photographed in 2003. My goals were modest – I simply wanted to find the beetle and voucher its current presence in northwestern Oklahoma (and if possible photograph it in the field with my new camera!). Before leaving, I wrote to Charles Lewallen, who graciously responded with details regarding the precise location and time of day that he had seen the beetle at Alabaster Caverns, and on the first Friday of June I followed behind Mike and his lovely wife Jane during our ten-hour drive out to Four Canyon Preserve. For three days, I roamed the mixed-grass prairie atop the narrow ridges and dry woodland on the steep, rugged canyon slopes of the preserve – always on the lookout for that telltale “flash” between the clumps of bluestem and grama, ever hopeful that one would prove not to be the ant or spider that it appeared to be (and, indeed, always was). Many tiger beetles would be seen – chiefly the annoyingly ubiquitous Cicindela punctulata (punctured tiger beetle), but celeripes would not be among them. Whether this is due to historical absence from the site or a more recent consequence of the wildfires that swept the area a year earlier is hard to say, but its absence at Four Canyon meant that I would need to make a quick, 1-day detour to Alabaster Caverns before rejoining Mike and Jane at Tallgrass Prairie Preserve in northeastern Oklahoma, where we planned to spend the second half of the week.

Photo details: Canon 65mm 1-5X macro lens on a Canon EOS 50D, ISO 100, 1/250 sec, f/13, MT-24EX flash 1/4 power through diffuser caps

Photo 4 - Cylindera celeripes on gypsum exposure at Alabaster Caverns State Park.

Arriving at Alabaster Caverns I was filled with nervous, excited anticipation. Would I find the species, as Charles Lewallen had, or would I get skunked? I kitted up and started walking towards the area where Charles wrote that he had seen the beetle, noting the annoying “Removal of plants and animals prohibited” sign along the way. I hadn’t taken ten steps off the parking lot when I saw it! I froze at first, hardly believing that I had found it that quickly, then started watching the tiny beetle as it bolted urgently from one grass clump to the next. Recalling my experience with this beetle in Iowa (and fearing I would lose it amongst the vegetation), I captured the specimen and placed it live in a vial – I would talk to the park staff later about taking the beetle, but for now I needed to guarantee I had a backup for the lab in case I was unable to get field photographs of the beetle. I started walking again, and within a few minutes I saw another one – okay, they’re here in numbers. I carefully took off my camera bag and assembled the components, all the while keeping my eye on the beetle, and then I began trying to do what last year had seemed impossible – getting field photographs. It was easier this time – the vegetation was not so dense, so I could keep an eye on the beetle as he darted from one clump to another. I tried to wait until he settled in an open spot, but it soon became apparent that just wasn’t gonna happen without a “helping” hand. I started blocking the path of the beetle as he tried to dart away and then removing my hand to see if he would stay put. There were a few false starts, where the beetle looked like he would sit still and then dart just as I was set to take the shot, but eventually it wore down and started sitting still long enough for me to shoot a few frames. Torn between the need to get as many photographs as possible and the desire to look for more beetles, I decided to look around more to see how common the beetle was. As I walked out into the shortgrass prairie above the canyons, I began to see adults quite commonly. Most often they were seen as they bolted out into the open from a clump of vegetation when disturbed by my approach. The substrate was red clay and gypsum – just as I had seen in Four Canyon Preserve, but unlike that area the clay exposures were heavily colonized by a mottling of green, blue, and gray lichens. It made the beetles almost impossible to see when they were not moving – even at close range! I spent about an hour taking photographs of several individuals, even managing to photograph one that appeared to be parasitized by what I take to be a dryinid hymenopteran.

Photo 5 - Cylindera celeripes with parasite (dryinid hymenopteran?).  Note also the ant head attached to right antenna.

Photo 5: Cylindera celeripes with parasite (dryinid hymenopteran?). Note also the ant head attached to right antenna.

After getting a sufficient series of photographs (is there really such thing?), I went to the park office hoping to convey the significance of this find to the Park Naturalist and to convince him/her to let me take some live individuals with me for another attempt at rearing. The Park Naturalist was out of the office, but the Park Historian was there. I could hardly contain my excitement as I explained to her what I had found, why it was so important, and my hope to try to rear the species with adults collected in the field. She not only responded as positively as I had hoped, but accompanied back out into the field so that I could show her the beetles. She told me it would be no problem to take some live individuals for rearing and to please let them know if there was anything else they could do to help me.  She then provided me with the day’s natural history “dessert” by pointing out a Mexican free-tailed bat (Tadarida brasiliensis) – Oklahoma’s state flying mammal – roosting up in the top of a nearby picnic shelter. Standing atop the picnic table put me within arm’s length of the little chiropteran – close enough to see his tiny little eyes looking quizzically back at me.

Photo 6 - Cylindera celeripes macrohabitat, Alabaster Caverns State Park, Oklahoma.  Note rather widely spaced clumps of vegetation (photo details: Canon 17-85mm zoom lens (17mm) on a Canon EOS 50D, ISO 100, 1/64 sec, f/8).

Photo 6 - Cylindera celeripes macrohabitat at Alabaster Caverns State Park. Note rather widely spaced clumps of vegetation.

It had begun sprinkling rain by then, so with some urgency I got my tools, extracted a couple of chunks of native soil and transferred them to the small “Critter Totes” that I had brought for the purpose, and began searching for live individuals to place within them. The beetles had become scarce as the drizzle turned to light rain, and by the time I had split about a dozen individuals between the two containers the rain was coming down hard enough to start puddling. I continued a last ditch effort to find “just one more,” but a lightning strike within a mile of the park put an end to that – the air now felt electric as I hurriedly walked back to the car (gloating unabashedly inside) and began the three-hour drive towards Tallgrass Prairie Preserve… (to be continued).

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Photo 7 - Cylindera celeripes microhabitat at Alabaster Caverns State Park. Note thick encrustation of lichens on clay substrate amidst white gypsum exposures.

Photo details:
#1-3, 5: Canon 100mm macro lens w/ 68mm extension on Canon EOS 50D, ISO 100, 1/250 sec, f/13 (photo 3, f/11), MT-24EX flash 1/4 power through diffuser caps.
#4: Same except Canon 65mm 1-5X macro lens, flash 1/8 power.
#6: Same except Canon 17-85mm zoom lens (17mm), 1/64 sec, f/8, natural light.
#7: Same except Canon 17-85mm zoom lens (35mm), 1/100 sec, f/7, natural light.

Copyright © Ted C. MacRae 2009

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