Insecta

Insects – Collembola, Protura, Diplura, Archaeognatha, Thysanura & Pterygota (winged insects).

Life at 8X—Guide to lepidopteran eggs on soybean

/ Ted C. MacRae / 5 Comments

Most of you are aware of my passion for beetles, but in reality that is just my evenings-and-weekends gig. By day, I am an agricultural entomologist conducting research on insect pests of soybean. I’m not sure how many latent soybean entomologists there may be among readers of this blog, but for this installment of “Life at 8X” I thought it would be interesting to feature eggs of several of the more important lepidopteran species that infest soybean in the U.S. Soybean is primarily a New World crop, and of the many lepidopteran species that attack soybean on these two continents, most belong to the great family Noctuidae (owlet moths). The species shown here include the most important species in North America, and in some cases South America as well.

See this post for details on photographic technique; however, note that most of the photos in this post that were shot at 8X have been cropped slightly (~10–15%) for composition (should I call this post “Life at 9X”?).

Anticarsia gemmatalis. Velvetbean caterpillar (“oruga de las leguminosas” in Argentina; “lagarta-da-soja” in Brazil) has long been the most important lepidopteran soybean pest throughout the New World. In North America its attacks are confined to the lower Mississippi River delta and southeastern Coastal Plain, but in South America nearly 100% of the soybean growing area is subject to attack. Eggs of this species are laid almost exclusively on leaf undersides throughout the canopy and are intermediate in size compared to the other species shown below (~7,000 eggs per gram). They are distinctive in their slightly flattened spherical shape and turn pinkish as they age and the developing larva takes form inside the egg.

Anticarsia gemmatalis—velvetbean caterpillar

Chrysodeixis includens (=Pseudoplusia includens). Soybean looper (“oruga medidora falsa” in Argentina; “lagarta falsa-medideira” in Brazil) was until recently primarily a North American pest with the same southern occurrence as velvetbean caterpillar. In recent years, however, it has gained importance in Brazil and northern Argentina as well, with its impact magnified by the capacity to develop resistance against most of the insecticides that have been used to control it. The egg of this species is quite small (~10,000 eggs per gram) and are are irregularly spherical with a somewhat translucent, crystalline appearance. Like velvetbean caterpillar, eggs of this species are laid almost exclusively on the leaf undersides, but the moths exhibit a clear preference for the middle or upper canopy depending upon plant growth stage.

Chrysodeixis includens (= Pseudoplusia includens)—soybean looper

Helicoverpa zea. Soybean podworm is better known in other crops as corn earworm, cotton bollworm, or tomato fruitworm (a testament to its polyphagous nature), and in South America the common names are even more diverse depending on both crop and country (“gusano bellotero,” “gusano cogollero del algodón,” “gusano elotero,” “isoca de la espiga en maíz,” or simply “bolillero” in Argentina; “lagarta-da-espiga-do-milho” or “broca-grande-do-fruto in Brazil). While it has long been considered a secondary pest of soybean in North America, recent years have seen a marked increase in its incidence across the mid-south growing areas. Unlike the above two insects, larvae of this species feed not only on foliage but also directly on pods, typically breaching the pod wall and consuming the developing seeds inside. This method of feeding not only causes direct yield impacts but also affords some protection to larvae from insecticide applications.

Also unlike the first two insects, eggs of this species can be laid anywhere on the plant—leaves (upper or lower surface), petioles, stems, pods, and even flowers. The eggs are rather large compared to the other species shown here (~3,500 eggs per gram) and assume a distinctive barrel shape when laid on the leaf. The creamy-white coloration, often with a light brown ring below the apex, is also distinctive compared to the previous two species. Eggs laid on pods tend to be attached to trichomes (hairs) rather than the pod surface, in which case they take on an almost perfectly spherical shape.

Helicoverpa zea—soybean podworm

Helicoverpa zea eggs on soybean pod

Heliothis virescens. Like the previous species, tobacco budworm has only recently gained attention as a pest of soybean. This importance, however, seems to be confined to Brazil (where it is known as “lagarta-das-maçãs”), while in North America it is usually found in combination with H. zea at minor levels. This is bad news for South American farmers; like soybean looper, tobacco budworm has developed resistance to all the insecticides that have been used against it in significant quantities. The oviposition and feeding behaviors of this species are very similar to those of H. zea, with eggs again laid on all parts of the plant and being very similar in appearance to those of H. zea except their slightly smaller (approx. 5,000 eggs per gram). In practical terms, eggs and young larvae of H. virescens and H. zea can be reliably distinguished only through species-specific immunoassay (Greenstone 1995) or feeding disruption bioassay using a diagnostic concentration of Bacillus thuringiensis ( Bailey et al. 2001).

Heliothis virescens—tobacco budworm

Heliothis virescens eggs on soybean pod.

As with H. zea, H. virescens eggs laid on pods tend to be stuck to hairs and assume a spherical shape.

This H. virescens egg has apparently died—note the shriveling and uniform black coloration.

Spodoptera frugiperda. Fall armyworm is a minor pest of soybean that rarely reaches economically damaging levels. However, its incidence in South America (where it is called “oruga militar tarde in Argentina and “lagarta-militar” in Brazil) has increased somewhat with the adoption of no-till cultivation of soybean. The species prefers grass hosts, but when these are knocked down by applications of post-emergence herbicides the larvae then move onto the soybean plants and continue feeding. Unlike any of the above species, eggs are laid in distinctive masses that are covered by abdominal setae and wing scales for protection. These eggs are also small (~8,500 eggs per gram), exhibit much finer and more numerous ridges than the above species, and are often colored orange, pink, or light green.

Spodoptera frugiperda—fall armyworm

Individual eggs inside the mass are covered by abdominal setae and wing scales.

REFERENCES:

Bailey, W. D., C. Brownie, J. S. Bacheler, F. Gould, G. G. Kennedy, C. E. Sorenson & R. M. Roe. 2001. Species diagnosis and Bacillus thuringiensis resistance monitoring of Heliothis virescens and Helicoverpa zea (Lepidoptera: Noctuidae) field strains from the southern United States using feeding disruption bioassays. Journal of Economic Entomology 94 (1):76–85.

Greenstone, M. H. 1995. Bollworm or budworm? Squashblot immunoassay distinguishes eggs of Helicoverpa zea and Heliothis virescens (Lepidoptera: Noctuidae). Journal of Economic Entomology 88(2):213–218.

Copyright © Ted C. MacRae 2012

Unexpected visitors

/ Ted C. MacRae / 8 Comments

Cicindela repanda (Bronzed Tiger Beetle) | Lewis Co., Missouri

In late July I began blacklighting on a weekly basis at different locations along the Mississippi River in an effort to gain more detailed information on the distribution of certain tiger beetles along that great watercourse. While attraction of tiger beetles to ultraviolet lights is well documented, it seems to me to be an underutilized method for collecting tiger beetles and recording distributions. Perhaps this is because only certain species are attracted to lights—principally members of the genera Ellipsoptera and Habroscelimorpha [and even one species, Habroscelimorpha striga (Elusive Tiger Beetle), that is seen almost exclusively at blacklights], while others, including the more commonly encountered and speciose genus Cicindela, are rarely attracted to lights. As a result, when I setup a blacklight on a sandy beach along the Mississippi River in La Grange in far northeastern Missouri, I expected to see Ellipsoptera cuprascens (Coppery Tiger Beetle), which I had seen there during the day many years ago, and hoped to see Ellipsoptera macra (Sandy Stream Tiger Beetle), which I have so far seen only in northwestern Missouri. I did not see either of these species, but what I did see was even more unexpected—Cicindela repanda (Bronzed Tiger Beetle).

Feasting on the bounty!

It is ironic that I should be so excited to see this species—it is only the most common species of tiger beetle in Missouri (and probably across much of eastern North America), where chokingly thick populations develop each summer along every waterway in the state. As a species, it is remarkable infidel when it comes to habitat selection, proximity to water appearing to be its only real requirement. I have seen them on virtually every type of stream/river/pondbank regardless of soil type—sand, mud, or any mixture of the two—and note them to be common even on concrete boat ramps (although I have yet to find larval burrows in the latter habitat!). Yet, I have never seen them at a blacklight! Perhaps it was just a matter of time, as until this year I myself hadn’t done much blacklighting for tiger beetles. Populations of this species build as the summer progresses, and it could be that once numbers reach their peak in mid- to late August, a few will find their way to a light that happens to be placed in their midst while the majority of individuals bed down in their overnight burrows.

A macerated bolus is all that remains of the caddisfly meal.

It’s easy to see what might attract them to the light other than the light itself—prey! At every location along the Mississippi River that I’ve blacklighted this summer, choking throngs of caddisflies inundate the sheet within the first half-hour after sunset. Piling up in layers beneath the stupefying light, the caddisflies are a limitless bounty of easy pickings for the tiger beetles, who greedily grab the hapless trichopterans in their toothy, sickle-shaped mandibles and then use their maxillae and digestive juices to macerate them to a juicy pulp that can be sucked dry. I have watched tiger beetle adults feeding on many occasions, but I never noticed until examining these photographs that the feeding beetles hold their antennae back and out of the way against their head and pronotum. Contrast the antennal position of the feeding beetles in the above photographs with the forward position of the antennae in the non-feeding beetles in the remaining photographs. Perhaps this is an adaptation to prevent the antennae from being grabbed and damaged by struggling prey.

A male in more natural-looking surroundings.

Recall also my recent lamentations about lacking good photographs of this species, due initially to lack of effort and later to a rare failure when I did try to photograph them. A half dozen individuals made their way to the light this night, and I was able to coax a few of them off the sheet and onto the surrounding sand for a few photographs in more realistic and natural surroundings. I still don’t consider these to be the photographs that I want for this species, as they do not show any of the thermoregulatory behaviors exhibited during the day such as stilting, sun-facing, or shade-seeking that make for such marvelously iconic tiger beetle poses. For that, I will need to give them another shot on a hot day while summoning every ounce of tiger beetle stalking skill that I can possibly muster. Still, these last two photos (and a few others not shown) are several steps above the single, frustratingly distant lateral profile shot that I had for this species before this night.

All jaws, eyes, legs, and hair!

Copyright © Ted C. MacRae 2012

Life at 8X—soybean aphid

/ Ted C. MacRae / 12 Comments

Although my first attempt at adding extension tubes to my Canon MP-E 65mm macro lens, effectively converting it from a 1–5X to a 1.7–8.0X lens, was nearly a year ago, it has only been recently that I’ve actually started experimenting with this combination to obtain high-mag photographs of very small insects in the field. The first example that I showed of such a photograph was a tiny seed weevil (Althaeus sp.) on its hibiscus host plant. I’ve since photographed a number of other insect subjects at high-mag using this setup and am getting a better feel for the capabilities—and limitations—inherent in using it. First, here is what the setup actually looks like:

Canon 50D body, MP-E 65mm macro lens on 68mm extension, MT-24EX twin flash w/ DIY diffuser.

Not the normal photo quality for this site (just a quick field setup photographed with my I-Phone), but it shows just how long the lens component becomes when fully extended to achieve 8X magnification. The camera is quite front-heavy, making the camera difficult to use hand-held, and the very shallow DOF (depth of field) due to the extreme level of magnification makes precise focusing difficult and magnifies the effect of any motion between the camera and subject. Obviously, one solution for these problems is to mount the camera on a tripod and place the subject on a stable surface; however, for reasons I’ve mentioned elsewhere, it is unlikely that I will ever take to bringing a tripod into the field, and the whole point of this exercise is to develop the capability for getting usable hand-held field photographs no matter what level of magnification they may require. As an alternative, I use a number of other techniques, discussed in my prior post on the subject, to stabilize the camera without using a tripod.

One of the recent subjects I photographed with this setup is the soybean aphid, Aphis glycines (order Hemiptera, family Aphididae). This distinctive Asian species has recently established in the U.S. as invasive pest of soybeans; adult females measure only 1–2 mm in length (and the nymphs are even smaller) and can quickly develop very high densities on the leaves and upper stems of soybean plants. The following photograph was taken at the camera setup’s minimum magnification of 1.7X and provides a typical view of adult aphids and their progeny:

Aphis glycines (soybean aphid) | Warren Co., Illinois

While the above photograph does a very good job of showing the colonial appearance of infestations by these aphids on soybean foliage, what about the aphids themselves? It would be nice to get a better look at individual aphids. The following photographs were all taken with the lens fully extended to achieve 8X magnification (and completely hand-held):

Adult female aphid—note the eye spots of the unborn nymphs visible within the body.

Another adult female navigates the hairs on the surface of the soybean leaf (I never knew soybean leaves were so hairy!).

A mother surrounded by her progeny. As above, eye spots of unborn nymphs can be seen inside her body.

These photographs are not without their problems—they are a bit soft, probably due to motion blur that results from the camera being hand-held and the extremely thin DOF that makes it difficult to get all of the desired components of the photos equally in focus. Lighting also is a challenge, as the very small subject-to-lens distance forces light from the flash to come from directly above or even behind the subject while minimizing front lighting (especially evident in the last photo with its straight down view). Nevertheless, these are decent, usable photographs that provide an uncommon view of these exceedingly tiny insects—without the encumbrance of carrying a tripod in the field, the time investment of studio photography and/or focus-stacking, or the expense of a microscope-mounted camera system (for those of us without access to such systems).

Copyright © Ted C. MacRae 2012

Shooting 8X hand-held in the field

/ Ted C. MacRae / 11 Comments

Just to prove it can be done, here is an uncropped photograph of the seed weevil Althaeus hibisci (or the closely related A. folkertsi) (order Coleoptera, family Chrysomelidae, subfamily Bruchinae). Adults of these species measure only 1.5–2.5 mm in length (Kingsolver 2004), yet this individual almost completely fills the frame:

Althaeus hibisci/folkertsi on Hibiscus moscheutos lasiocarpus | Route 66 State Park, St. Louis Co., Missouri

I achieved 8X magnification by stacking 68 mm of extension tubes under my Canon MP-E 65mm 1–5X macro lens and extending the bellows of the lens out to its maximum. Shooting 8X is not for the timid—the small subject to lens distance complicates lighting (full flash required), and even finding the subject in the viewfinder can be next to impossible. However, doing it hand-held in the field requires more than just courage and patience—good bracing techniques to minimize movement by and between the camera and the subject are essential. Here is how I do it:

  • I sit down, prop my knees up, and rest the camera in the crotch between my knees (the camera quickly becomes very heavy since it’s being held by only one hand—see next bullet) while positioning it near my face. If possible, I lean back against something as well to provide even more stability, although this is often not possible depending on field conditions.
  • I hold the leaf or flower supporting the subject in my left hand. Subjects this small are rarely going anywhere (or if they are skittish then I use the same slow, deliberate techniques that I use with larger skittish insects), so it is possible to hold the leaf or flower and position the subject right in front of the lens. Hand holding the subject’s support also affords the ability to micro-adjust the position and angle of the subject for optimum composition or to adjust for movement by the subject (easier than trying to track it by moving the lens). In this case of the photo featured here, I detached the leaf with the beetle from the plant (use small scissors to snip the leaf petiole, as this avoids the “jolt” that happens if you try to pick the leaf and which usually results in the subject fleeing). In other cases, I leave the leaf attached and carefully “pull” it towards me to hold it steady.
  • I look through the viewfinder and brace my left wrist (yes, the same hand that is holding the subject) on the underside of the lens, then slowly move the subject towards the lens with my fingers until I see movement and can micro-adjust for proper focus. Bracing your wrist against the lens is key—it is nearly impossible to hold the subject steady in front of the lens without bracing your wrist against it. In effect, this “fixes” the subject to the lens. Also, before I begin looking for the subject through the viewfinder I study its position on the leaf and look for “landmarks” that I can recognize when looking through the viewfinder to minimize the time needed to find the subject (the more time you spend looking for the subject, the greater the chance it will move or flee). Again, the subject to lens distance is very small, but with practice you’ll get a feel for precisely how far from the lens you need to place the subject.
  • I hold my breath and micro-adjust the subject position to nail the focus (usually on the eye) and then fire a shot. If it takes too long to get the focus I exhale and try again, as body shake will only get worse once it starts. Important: After taking the first shot, do not move the hand holding the subject as you look at the image preview and/or histogram—the first shot rarely has the settings precisely where you need them, and keeping the subject in place prevents a lot of re-searching after making the needed setting adjustments with the right hand.

Other than lighting, nailing the focus is the most difficult aspect of shooting hand-held at such high magnifications. The more relaxed and stable you can keep the rest of your body, the less hand movement you’ll experience while holding the subject and the greater chance you have of hitting the focus. Again, a fully extended MP-E lens on 68 mm of extension tubes becomes very heavy very quickly when held in one hand (even when resting on your knees), so expect your forearm muscles to give out quickly until you have a chance to strengthen them through practice.

I use these same techniques to some degree at lower magnifications as well—certainly for anything above 2X. I’m interested in doing a lot more 8X photography, however, because there is a whole world of tiny insects that are not being photographed due to their very small size. These insects are no less fascinating and beautiful than their larger, more oft photographed brethren.

Finally, you might be asking why I don’t just carry a tripod or collect subjects and bring them back to the studio for more controlled conditions. There are many photographers who advocate the use of tripods, but I’m not one of them. I am first and foremost an entomologist, and when I’m in the field I’m generally already carrying at least a net and other equipment for collecting insects. There are opportunity costs involved if I also try to lug a heavy tripod with me. What’s that? I could leave it in the car and then go get it when I need it? Honestly, I would pass on a lot of shots if I had to go back to the car to get something for it. The same goes for studio photography—there are many shots I would simply pass on if getting them meant that I needed to collect subjects, keep them in good condition for the duration of the trip (which might be days or more), and then setup in a studio. Moreover, there are many shots—specifically regarding behavior—that would be impossible with collected subjects. But really, it has mostly to do with what I want to be and portray as an insect photographer, and that is somebody who has the ability to photograph unconfined subjects exhibiting natural behaviors in their native habitats. Having the ability to shoot 8X hand-held in the field if I want to gives me more options and makes me a better photographer.

Do you have any special bracing or stabilizing techniques that you use for high-mag hand-held macrophotography? If so I’d love to hear about them.

REFERENCE:

Kingsolver, J. M. 2004. Handbook of the Bruchidae of the United States and Canada. U.S. Department of Agriculture, Technical Bulletin 1912, 2 volumes, 536 pp.
 
Copyright © Ted C. MacRae 2012

Very cozy tigers!

/ Ted C. MacRae / 2 Comments

In my post Very wary tigers!, I spoke of the frustrations of trying to photograph tiger beetles when conditions of temperature and terrain conspire to make them too wary to approach. This is a common feature of tiger beetle photography in general, but the problem seems to reach its zenith with the “wet sand beach” species—most species inhabiting these habitats tend to be “summer species” active during the hottest part of the season, and their habitats tend to be virtually devoid of any vegetative cover that can be used to the photographer’s advantage. A blazing sun on hot, open sand is not conducive to photographing anything! Still I try, and on that particular day I did manage a few relatively distant photographs of two species, Cicindela repanda (Bronzed Tiger Beetle) and C. hirticollis shelfordi (Shelford’s Hairy-necked Tiger Beetle) but none at all of a third species that was present on the beach, Ellipsoptera cuprascens (Coppery Tiger Beetle).

Ellipsoptera cuprascens (Coppery Tiger Beetle) | New Madrid Co., Missouri

Well, there is always more than one way to skin a cat (or a tiger), and as can be seen in these photographs I took a different approach to that latter species that allowed me to obtain several quite decent photographs of both males and females. Not long after that frustrating day at Cape Rock Park, I found myself again in southeastern Missouri with an opportunity to do some night collecting. It may not be widely known, but certain species of tiger beetles are also active at night and can actually be attracted to ultraviolet (UV) lights. This is particularly true of species in the genus Ellipsoptera, which as a group seem to depend almost exclusively on coastal and fluviatile sand habitats. I have used UV lights in the past to attract nocturnally active species of tiger beetles for photography (see Return to Nowhere), and since I had seen E. cuprascens a few years ago at Steward Towhead in New Madrid County I thought this might be a good spot to try again for photographs of that species.

The relatively coarsely and densely punctate elytra distinguish E. cuprascens from E. macra.

“Might be a good spot” turns out to be quite the understatement, as I have never seen E. cuprascens in such numbers as I did that night! Seeing the species common at the sheet guarantees that individuals will also be found milling around on the ground in the immediate vicinity of the sheet, and unlike during the heat of the day when their bodies shift to thermal overdrive, adults at night are much easier to approach due to the cooler temperatures and the distraction of abundant, easily captured prey sitting transfixed in their UV light-induced stupor. Of course, night photography brings its own set of challenges, primarily (for me) the need to use the camera flash head lamps for focusing—I often find myself repeatedly aborting a shot because the lamps turned off automatically before I had a chance to find the subject and compose the shot to my satisfaction. Still, this is a minor inconvenience compared to the exasperation of subjects blasting across the hot sand when your approach comes within 12 feet!

Males mandibles are modified for grasping the female pronotum during mating.

Ellipsoptera cuprascens is very closely related to E. macra (Sandy Stream Tiger Beetle—see The last tiger beetle), which it resembles greatly and whose ranges overlap here in Missouri (although the latter is far less commonly encountered than the former). The photos in this post show the relatively coarser and denser punctures on the elytra that distinguish E. cuprascens from E. macra, as well as their somewhat shinier surface and distinctly more coppery color. The rounded elytral apices of the female (middle photo) also serve to distinguish the species from E. macra, in which species the elytra of the females come to a point at the suture (Pearson et al. 2006). Note also the sexual dimorphism in the labrum and mandibles of the female (first photo) and male (last photo), with the mandibles relatively longer and slightly curved and the labrum shorter in the latter. Presumably this is related to the use of the mandibles by the males in grasping the female pronotum during mating—the longer, curved mandibles are shaped to precisely fit the contour of the female’s pronotum, while the shorter labrum allows the mandibles to gain better purchase farther down on the side of the female’s pronotum (Pearson and Vogler 2001).

REFERENCE:

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.

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.

Copyright © Ted C. MacRae 2012

Very wary tigers!

/ Ted C. MacRae / 8 Comments

In late July I found a new tiger beetle site in southeastern Missouri—a small sandbar along the Mississippi River near Cape Rock Park on the north side of Cape Girardeau. I originally went to the park to look for Cylindera cursitans (Antlike Tiger Beetle), two specimens of which my friend and colleague Kent Fothergill had found in the collection of a local lepidopterist (MacRae et al. 2012). I thoroughly searched the areas that looked suitable for that species, but to no avail. I did, however, spot the sandbar down by the river and knew immediately that it had good potential for several species typically found in such habitats. Even before hiking down the rocky embankment I figured I would see Cicindela repanda (Bronze Tiger Beetle)—dreadfully common along almost every waterway in the state. What I was really hoping to see, however, were some of the more specialty species found only in wet sand habitats along the big rivers of the state—the Missouri and mighty Mississippi.

”Stilting” and ”sun-facing” by Cicindela hirticollis shelfordi | Cape Girardeau Co., Missouri

Predictably, C. repanda was present and abundant, but it wasn’t long before I spotted some individuals that looked just a little bit different—stockier and with the white markings a little more distinct. A closer look confirmed that these were C. hirticollis shelfordi (Shelford’s Hairy-necked Tiger Beetle). It had been a while since I’d seen this species, and it occurred to me that the only photos I had of it were taken with my point-and-shoot prior to getting my dSLR setup. I then realized also that I didn’t even have good photographs of C. repanda—I’ve been so focused on photographing rare and unusual species over the past few years that I’ve completely neglected photographing our state’s most common resident.

Sand bar habitat along the Mississippi River | Cape Girardeau Co., Missouri.

Over the years, I’ve learned a number of tricks that have allowed me to be fairly successful at approaching tiger beetles closely for photography—working a population to find that one slightly more cooperative individual, and then working that one individual until it becomes accustomed to my presence, perhaps allowing it to “hide” under debris before carefully removing its cover or even “trapping” it in a relatively confined area until it settles down enough to allow photographs. But nothing, not a single thing I tried, worked on this day. As it was through much of July and early August, temperatures were extreme—already well into the 90s despite my mid-morning arrival. Combined with the wide open spaces and a blazing hot sun, the beetles were already extremely active and very wary. The sandbar itself offered little help in corralling the beetles—stark, barren, devoid of any debris or other potential shelters that could be used to my advantage. Stubbornness prevented me from accepting this fact, so I spent the good part of two hours slowly stalking each beetle that looked like it might cooperate, only to have it fly before I could even get down on all fours or, once I did, run incessantly to the point that it was almost impossible to settle it in the frame—much less compose a decent closeup shot. Eventually I decided that the only way I was going to get a beetle standing still in the frame with any degree of closeness was to approach it from the front and try to catch it in one of its intermittent “stilting/sun facing” poses—a thermoregulatory behavior that tiger beetles employ when the sun heats the soil surface to temperatures that would be lethal for many other insects. The first shot in this post is the best of that type that I could manage (although I like its composition very much—I just wish I’d been able to get some closer shots as well).

The ”C”-shaped humeral lunule identifies this individual as Cicindela repanda.

As suggested above, C. repanda and C. hirticollis are quite similar in appearance, and at least in Missouri the latter is always found in association with the former, though only in wet sand habitats along the big rivers and not nearly in the same numbers as C. repanda. Until one develops a feeling based on “gestalt” it can be difficult to pick out individuals of C. hirticollis amongst the commoner C. repanda. I’ve already mentioned their slightly huskier build and somewhat bolder white markings, and C. hirticollis also tends to exhibit a slightly more coppery cast to the body. The surest character to use, however, is the “G”-shaped humeral lunule, which is the white marking on the “shoulders” of the elytra just behind the pronotum. The posterior portion of this marking is nearly transverse and usually angles sharply anteriorly on its inner edge. By contrast, in C. repanda this marking is always “C”-shaped and never curls forward on its inner edge. These characters can be compared in the lateral profile photos of the two species above and below (though not as closely as I would like).

The ”G”-shaped humeral lunule identifies this individual as Cicindela hirticollis.

I should mention that there was one other big river specialty species present on the sandbar—Ellipsoptera cuprascens (Coppery Tiger Beetle). I saw only a few individuals of this species and couldn’t get close enough to one of them to even fire off a single shot. For this species, however, I still had one more trick up my sleeve that allowed me to photograph it to my heart’s content (no, not capturing one and confining it in a terrarium!)…

REFERENCE:

MacRae, T. C., C. R. Brown and K. Fothergill. 2011. Distribution, seasonal occurrence and conservation status of Cylindera (s. str.) cursitans (LeConte) (Coleoptera: Cicindelidae) in Missouri.  CICINDELA 43(3):59–74.

Copyright © Ted C. MacRae 2012

And the winner is…

/ Ted C. MacRae / 13 Comments

Okay, time to fess up on which of my photos was selected for the 2013 ESA World of Insects Calendar, but before I do let me say that getting readers’ comments on which one they thought was selected proved to be a very interesting exercise. The final tally is as follows (I gave ½ a vote for mentions of a photo as a second choice):

1. Trimerotropis saxatilis nymph – 4½ votes
2. Crossidius coralinus fulgidus – 3½ votes
3. Tetracha floridana – 3 votes
4. Buprestis rufipes – 2 votes
4. Edessa meditabunda eggs – 2 votes
6. Megaphasma denticrus – 1 vote

My personal favorites were Buprestis rufipes, Crossidius coralinus fulgidus and Tetracha floridana, with the second having what I thought was the best “calendar appeal.” I also thought the Trimerotropis saxatilis was strong for its natural history back story. It thus comes as no surprise that these were the top four vote-getters among those who commented.

The two photos that did not receive any votes are interesting—Spissistilus festinus, because the post containing that photo is one of the Top 5 posts on this blog (based on page views); and Cicindela formosa generosa, because that was the photo selected by ESA for their 2013 Calendar! I went back and forth on whether to include the photo in the final selections, but it won out over some others I was considering because of its composition—not many tiger beetle closeups contain as much scale and depth. I guess that’s what ESA like about it as well, but whatever the reason it seems I need to develop a better sense of what photo judges are looking for.

Since nobody guessed the correct photo, I’m going to give all who commented 5 “participation” points, and those of you who used italics with scientific names will get an additional 2 bonus points. Brady Richards maintains his spot atop the overalls in BitB Challenge Session #6 with 66 points, but Mr. Phidippus‘ 58 points moves him into second place over Sam Heads with 54 points.

For those who did not vote for this photo (or, everybody!), maybe access to this 1680×1120 version of the photo (click to enlarge) will help change your minds.

Cicindela formosa generosa (Coleoptera: Carabidae: Cicindelinae) – eastern big sand tiger beetle

Copyright © Ted C. MacRae 2012