Month: September 2014

Sunset beetles

/ Ted C. MacRae / 4 Comments
Acmaeodera immaculata? | vic. Vogel Canyon, Colorado.

Acmaeodera immaculata? (family Buprestidae) | vic. Vogel Canyon, Colorado.

Regular readers of this blog know that I am fond of natural sky backgrounds for insects found during the day on flowers and foliage. Not only does the sky provide a clean, uncluttered background that allows the subject to stand out, it also gives the photo a more appropriate temporal flavor—i.e., photographs of diurnal insects should look like they were taken during the day. It’s a little bit tricky setting the camera to allow flash illumination of the subject while still allowing the sky to register as well, but I find such photographs more pleasing and interesting than those with a jet-black background, typical in flash macrophotography, and far more pleasing than those with a jumble of sticks and weeds cluttered behind the subject. These days my daytime insect photos almost always incorporate a blue-sky background (examples here and here) unless: 1) I actually photographed the subject at night (examples here and here); or 2) I wish to highlight an intensely white or delicately structured subject (examples here and here).

Aulicus sp. | vic. Black Mesa, Oklahoma

Trichodes oresterus? (family Cleridae) | vic. Black Mesa, Oklahoma

But what about in between day and night—specifically, sunset? Incorporating a sunset sky into a flash-illuminated macrophotograph is even trickier than incorporating a blue midday sky because the central problem—low light levels—is magnified. Blue sky photographs challenge the fast shutter speeds and high f-stops usually needed for macrophotographs, but relatively minor adjustments to ISO, shutter speed, and f-stop are usually sufficient to allow the sky to register while still being able to maintain depth of field and minimize motion blur. At sunset, however, because there is much less illumination of the sky, more aggressive settings are often required to allow the sky to register on the camera sensor—settings that can sometimes result in too much motion blur or insufficient depth of field. These problems can be mitigated to some degree with the use of a tripod (and very cooperative subjects), but for dedicated “hand-held” enthusiasts like myself this is not an option. Why bother? Because the results can be spectacular! The setting sun often creates stunning colors not seen at other times of the day and offer a change of pace from blue skies, which, like black backgrounds, can start looking rather monotonous if used exclusively in one’s portfolio.

Linsleya convexa | vic. Vogel Canyon, Colorado

Linsleya convexa (family Meloidae) | vic. Vogel Canyon, Colorado

The photos featured in this post were taken during several sunsets on a trip earlier this past summer through Colorado and Oklahoma. I especially like the jewel beetle (Acmaeodera immaculata?) photograph—technically it has good focus and depth of field and a pleasing composition, but I really like the color coordination between the beetle, flower, and sky. The checkered beetle (Trichodes oresterus?) photograph is also very pleasing, especially the detail on the beetle, although the color of the sky is only somewhat different than a more typical daytime blue. The blister beetle (Linsleya convexa) photograph is probably the most problematic technically due to slight motion blur and being slightly off-focus at the eye—not surprising since of the three this photo had the lowest light conditions. However, the color contrast between the sky and subject make this a nevertheless striking image.

If you have experience with ambient light backgrounds in flash macrophotography, your comments on approaches you’ve taken to deal with reduced light situations will be most welcome.

© Ted C. MacRae 2014

A truly disturbed garden spider

/ Ted C. MacRae / 15 Comments
Argiope trifasciata vibrating web in response to disturbance.

Argiope trifasciata shaking its web in response to being approached.

This past weekend I made a trip to the White River Hills region in extreme southwestern Missouri. My goal was to find additional localities of the prairie tiger beetle (Cicindelidia obsoleta vulturina), which inhabits dolomite glades in the area and is disjunct from the main distribution in Texas and Oklahoma. As I was checking a particularly large glade complex in Roaring River State Park, I came upon this banded garden spider (Argiope trifasciata) that had spun its web across the span of branches from a gum bumelia tree (Sideroxylon lanuginosum). As I approached the spider the web began moving back and forth quite vigorously, and it occurred to me that there was not nearly enough wind for the web to be shaking to such degree. I stood still, and eventually the shaking stopped and the web became still again. To test whether it was really the spider shaking the web intentionally, I raised my net to one side and drew it closer to the spider, and once again the web began shaking back and forth just as vigorously as before. I watched the spider closely as the web shook, and I could see that the spider was actually flexing its two front pairs of legs back and forth to cause the shaking. It was clear at this point that the spider was doing this in response to my approach, probably as a defensive reaction to a perceived threat.

I suppose I have seen this behavior before but always assumed the web was just shaking in the breeze. Not until this time, with no wind to speak of and the web shaking quite rapidly, did it become clear to me that this was actually an intentional behavior exhibited by the spider. Eisner (2005) also notes this behavior, stating that Argiope spiders often engage…

…in a bobbing action, whereby through a quick flexion of its legs it sets the web into vibration, making itself a blurred target that is hard to grasp.

The photos used to make this animated gif were not easy to get. The spider was situated in a rather high and awkward-to-reach spot, and the iPhone had difficulty focusing on the spider while it was in motion. I overcame these problems by setting myself in a stable position, holding the iPhone in place, zooming the screen slightly (about 33%) and locking focus on the spider while it was still, and then asking my field buddy (Steve Penn) to approach the spider to trigger shaking. Once it began shaking it was a matter of holding down the shutter while keeping myself and the camera still long enough for a sufficient burst of photos (eight photos were used in this gif).

REFERENCE:

Eisner, T. 2005. For the Love of Insects. Harvard University Press, Cambridge, Massachusetts, 448 pp. [Google Books].

© Ted C. MacRae 2014

The lesser of two jewels

/ Ted C. MacRae / 1 Comment
Chrysobothris dentipes on exposed root of Pinus virginiana | South Cumberland State Park, Tennessee

Chrysobothris dentipes on exposed root of Pinus virginiana | South Cumberland State Park, Tennessee

A couple of months ago I wrote a post about Chrysobothris orono, a magnificent jewel beetle that I had the opportunity to see earlier in the year. Fellow buprestophile Joshua Basham and his colleague Nadeer Youssef had managed to find this very uncommonly encountered species breeding in exposed roots of Virginia pine (Pinus virginiana) on the edges of high bluff tops in South Cumberland State Park, Tennessee. I traveled to the site with them this past May and was rewarded with one specimen of the species, two Buprestis species that I’d not collected before (B. striata and B. salisburyensis), several photographs of each, and numerous memories. Chrysobothris orono was not, however, the only species in the genus seen that day. We also encountered numerous individuals of another species, Chrysobothris dentipes, on the same Virginia pines that were hosting C. orono, B. striata, and B. salisburyensis. Like C. orono, nearly all of the individuals seen were not on the trunks and branches of the pines, but on dead, exposed roots of the pines.

Presumed Chrysobothris dentipes adult emergence hole in exposed root of Virginia pine.

Presumed Chrysobothris dentipes adult emergence hole in exposed root of Virginia pine. Note pile of frass on the ground below the hole, suggesting that the adult emerged shortly before this photo was taken.

Unlike C. orono, however, which has only been recorded from a handful of states/provinces along the eastern seaboard and around the Great Lakes (and, now, Tennessee—MacRae & Basham 2013), C. dentipes is one of the widest ranging species in the genus, occurring throughout much of the U.S. & Canada and even the West Indies and northern Mexico (Fisher 1942). Throughout this expansive range, C. dentipes larvae develop in dead pine wood, although they have been reared also from tamarack (Larix laricina) and balsam fir (Abies balsamea) (Fisher 1942, Dearborn & Donahue 1993). I remember my excitement at collecting this species for the first time back in the 1980s in Missouri on log piles and slash from logging operations in the shortleaf pine (Pinus echinata) forests of southern Missouri. Eventually I realized how common and widespread a species it is, as it was the one species I could almost always count on seeing whenever I examined recently dead pines wherever I went.

The flattened body, dull coppery color, and partly yellow antennal segments make this a distinctive eastern U.S. species.

The flattened body and partly yellow antennal segments make this a distinctive species in the field.

The specific epithet (“denti-” meaning tooth, and “pes” meaning foot) apparently refers to the large spine on the front femora, although many species of Chrysobothris exhibit this character. This was one of the earliest described species in the genus, so perhaps other species with spined femora hadn’t been seen yet, or maybe the name refers to the toothed outer margin of the femoral spine rather than the spine itself. In any case, the species is rather distinctive and easy to identify in the field by its moderately large size, somewhat flattened body, and overall matte appearance. The clincher are the antennae, which may not be easy to see in the field but, unlike any but a few other very dissimilar species, have the outer segments partly brownish-yellow in color. Like most Chrysobothris species, adults are very “zippy” and alert in the field, the males running rapidly in short bursts when searching logs for females and both sexes quick to take flight when approached. While the adults in these photos are fairly conspicuous on the wood on which they are sitting, their coloration and surface sculpturing actually serve a cryptic function and make them very difficult to spot on rough pine bark where they are normally encountered.

REFERENCES:

Dearborn, R. G. & C. P. Donahue. 1993. An annotated list of insects collected and recorded by the Maine Forest Service, order Coleoptera, beetles. Maine Forest Service, Department of Conservation, Insect and Disease Division No. 32, 102 pp.

Fisher, W. S. 1928. A revision of the North American species of buprestid beetles belonging to the genus Agrilus. U. S. National Museum 145, 347 pp.

MacRae, T. C. & J. P. Basham. 2013. Distributional, biological, and nomenclatural notes on Buprestidae (Coleoptera) occurring in the U.S. and Canada. The Pan-Pacific Entomologist 89(3):125–142 [pdf].

© Ted C. MacRae 2014

A striking mallow caterpillar

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Tarache delecta ("mallow caterpillar") on Hibiscus lasiocarpus | Hickman Co., Kentucky

Tarache delecta (“mallow caterpillar”) on Hibiscus lasiocarpus | Hickman Co., Kentucky

Last month while searching stands of Hibiscus lasiocarpus (hairy rose mallow) in western Kentucky, I encountered this rather large caterpillar feeding on the foliage. I presumed that something as large and striking in appearance as this should be a cinch to identify by scanning through photos on BugGuide, and not surprisingly I found photographs (here, here and here) of two very similar looking caterpillars from Oklahoma posted by Charles Schurch Lewallen. None of the photos, however, had an identification associated with them other than subfamily Acontiinae (family Noctuidae). The contributor mentioned in one of the photos that he had found nothing similar in the Wagner (2005) “bible” (a book that I do not yet own but hope to soon). Armed with this scant information (but definitive knowledge of its host plant), I searched Noctuidae of North America and settled on Tarache delecta as a good possibility. According to that site, T. delecta is the only member of the Acontiinae that feeds on plants in the genus Hibiscus. The site references Crumb (1956) for a larval description, but more useful was a plate of black & white photos that I found in Weiss (1919) and that seemed to be a good match for the species I had photographed. Weiss (1919) refers to the larva as the “mallow caterpillar” and notes that full grown larvae are 34–36 mm in length and dark purple with black spots edged with orange—consistent with the caterpillar shown here.

Apparently this species has been considered a pest of ornamental mallows. Weiss (1919) notes that the larvae feed on the upper and lower leaf surfaces usually near the margins, making large holes in the leaves and sometime devouring parts of the bracts around the buds. I will also note that, in recommending control of the caterpillars, he states that “there does not seem to be any reason why spraying with arsenate of lead should not be successful.” My, how times have changed!

REFERENCE:

Crumb, S. E. 1956. The larvae of the Phalaenidae. U. S. Department of Agriculture, Technical Bulletin 1135, 356 pp. + 10 plates [Google Books].

Wagner, D. L. 2005. Caterpillars of Eastern North America: A Guide to Identification and Natural History. Princeton University Press, Princeton, New Jersey, 512 pp. [Amazon].

Weiss, H. B. 1919. The more important insect enemies of the rose-mallow in New Jersey. New Jersey Department of Agriculture, Bureau of Statistics and Inspection Circular 25, 9 pp. + 4 plates [Google Books].

© Ted C. MacRae 2014

Not quite adult

/ Ted C. MacRae / 3 Comments

For the past few years I’ve had research plots in northwestern Tennessee. Each summer, once a month or so, I make the 5-hour drive to the site and spend the afternoon taking data. Any normal person would then check in to their hotel room in town, watch television, and make the drive back to St. Louis the next morning. Of course—I’m not normal, I’m an entomologist! The southeastern lowlands of Missouri, where over the years I’ve found (and continue to find) a number of good spots for collecting insects, are tantalizing close. Instead of retiring immediately to my hotel room, I’d rather head back to the lowlands and find a good spot for setting up a blacklight. It might be midnight before I finally get to a hotel room, but it’s all worth it. Some of the most interesting insects that I’ve featured here during the past few years have come to blacklights on one of these trips, including the primitive longhorned beetles Parandra glabra and Mallodon dasystomus and adult male bagworms, Thyridopteryx ephemeraeformis.

Subadult female, poss. Maccaffertium sp. | Mississippi Co., Missouri

Subadult female mayfly (prob. Maccaffertium sp.) | Mississippi Co., Missouri

Most of the spots I’ve found are located along the Mississippi River, a downside of which is the overwhelming abundance of aquatic insects that are often attracted to the lights. Caddisflies (order Trichoptera) are the worst, sometimes swarming the lights with such frenetic abundance that to check the sheets one must button the collar, hold the breath, dash in quickly to look at the sheet, and retreat just as quickly lest the fluttering hordes find their way up the nostrils, down the ear canals, and into the eyes. Mayflies (order Ephemeroptera) also can be attracted in great numbers, although they tend to be, fortunately, much calmer and better behaved on the sheet than their trichopteran counterparts. Normally, I pay little attention to these insects other than what is required to avoid breathing them—their abundance almost makes them unnoticeable. On one particular night in early August, however, my eyes caught the soft glow of a ghostly-white insect sitting on the underside of a leaf some yards away from the light. I looked closer to see it was a mayfly, and so pale was its coloration that I knew it would make for a striking photograph against the black night sky.

The reason for its milky-white coloration is due to a unique aspect of mayfly developmental biology—they are the only insects to develop fully functional wings before their final molt to adulthood. This stage, called the sub-adult or subimago, emerges from the water where it spent the past year as a nymph (also called a naiad) and flies to nearby vegetation, but it is still not mature. One additional molt is required, wings and all, before the insect finally reaches adulthood and can spend the few remaining hours of its life in single-minded pursuit of a mate. Sub-adult mayflies are distinguished from their adult counterparts by their paler coloration and opaque rather than clear wings. We can also tell that this individual is a female because no claspers are visible at the tip of the abdomen (which males possess for mating) and its relatively small eyes (the eyes of males almost completely cover their head).

My thanks to Dr. Robert Sites, who initially suggested this might be a species in the family Heptageniidae, and to Roger Rohrbeck for confirming my subsequent identification as probably belonging to the genus Maccaffertium.

© Ted C. MacRae 2014

First-ever BitB “Reader’s Poll”

/ Ted C. MacRae / 10 Comments

For seven years now I’ve been conducting this experiment called Beetles in the Bush. In that time I’ve written nearly 1,000 posts (with the help of a few guest authors), posted nearly 3,000 images, contributed or entertained over 10,000 comments, and watched the site creep ever closer to its millionth hit! This might leave you wondering why I should, now, be asking readers to provide feedback on why they visit BitB and what they like most (or least) about it. The reason is simple—blogging is less popular now than it was a few years ago. Comments and readership are both in decline (not just here, but across the platform), and the trend has left few clues about who the remaining readership is and what they are interested in. If I know clearly what readers want, it will be easier for me to provide it. That is not to say I expect (or even could) drastically change my content or its focus. However, if I know a certain topic is more popular than others I can give that topic priority, or if nobody really reads the “long-reads” I can skip them altogether. I hope you’ll indulge my curiosity by participating in the five short polls below that need only a few anonymous clicks of the mouse—no written responses required. Of course, if you wish to provide written feedback in the comments section it will be most appreciated. And, as always, thank you for your readership.

© Ted C. MacRae 2014

One-shot Wednesday: swamp milkweed leaf beetle

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Labidomera clivicollis on Asclepias incarnata | Hickman Co., Kentucky

Labidomera clivicollis on Asclepias incarnata | Hickman Co., Kentucky

Technically this photograph of Labidomera clivicollis (swamp milkweed leaf beetle) doesn’t qualify as a “one-shot”, as I did take a few other shots as well. However, this was the only shot out of the handful that I didn’t throw away. It’s not perfect—the right front and left rear legs are raised awkwardly, and the lighting is a bit harsh. However, the important parts of the beetle are in focus, the composition is acceptable (with all parts of the beetle within the frame), and there is pleasing value contrast between the orange and black body of the beetle, the green plant on which it sits, and the clear blue sky in the background. The plant’s flowers have even added a smidgen of pink. All of the other photos lacked either focus or composition, neither of which are easily “fixable” in post-processing. The difficulty in getting a better photo is a result of the beetle’s refusal to settle down and stop walking and my lack of desire to spend an inordinate amount of time waiting for this to happen as opposed to finding the insect I was really looking for (more on that in a future post).

I found this beetle on swamp milkweed (Asclepias incarnata) in Hickman Co., Kentucky. As the common name suggests, swamp milkweed is one of the main hosts for this rather large beetle (at least, by leaf beetle standards). However, they can and do feed and develop on other milkweeds, especially common milkweed (A. syriaca), and even related genera such as swallow-wort (Cynanchum) and twinevine (Funastrum) (all belonging the family Asclepiadaceae).

Labidomera clivicollis is part of the orange and black milkweed mimicry complex, which includes monarch butterfly (Danaus plexippus), red milkweed beetles (Tetraopes spp.), large milkweed bug (Oncopeltus fasciatus), small milkweed bug (Lygaeus kalmii), milkweed assassin bug (Zelus longipes), and others. Most of these insects have evolved mechanisms for avoiding or detoxifying cardenolides (produced by milkweed as a defense against herbivores) and sequestering them within their bodies for their own defense against predators. This represents a classic example of a Müllerian mimicry ring, in which multiple insect species—sometimes from different families and even different orders—share a common warning color. Predators learn to avoid these colors and, thus, avoid all of the species within the mimicry ring.

© Ted C. MacRae 2014

My, what busy palps you have!

/ Ted C. MacRae / 6 Comments

In mid- to late summer, the swamps of southeast Missouri and adjacent areas along the Mississippi River become awash in color as stands of hairy rose mallow (Hibiscus lasiocarpus) put forth their conspicuous, white and pink blooms. I’ve been waiting for the mallows to bloom this year, as there is one particular beetle associated with plants in this genus that I have been keen to photograph since I first picked up a real camera a few years ago, to this point without success. My first attempt this year came in early August as I noted the tell-tale blooms while passing through extreme western Kentucky. I was foiled again (but would succeed the next day—more on this in a future post), but as I tiptoed over the soggy ground searching through the lush foliage, I saw a small, brightly colored cricket with curiously enlarged mouthparts. Even more interesting was the constant, almost frenetic manner in which the insect was moving these mouthparts. My first attempts to detach the leaf on which it was moving spooked it, and it jumped to another leaf, but I persisted and finally succeeded in detaching the leaf with the critter still upon it and maneuvering it up towards the sky for a few photographs.

Phyllopalpus pulchellus (red-headed bush cricket) | Hickman Co., Kentucky

Phyllopalpus pulchellus (red-headed bush cricket or “handsome trig”) | Hickman Co., Kentucky

It didn’t take long to identify the cricket as Phyllopalpus pulchellus, or “red-headed bush cricket” (family Gryllidae). This species, also known as the “handsome trig” on account of its stunning appearance and membership in the subfamily Trigonidiinae, is distinctive among all North American orthopterans by its red head and thorax, pale legs, dark wings, and—as already noted—highly modified maxillary palpi with the greatly expanded and paddle-like terminal segment. According to Capinera et al. (2004), adults appear during mid- to late summer near streams and marshes on vegetation about one meter above the ground—precisely as this individual was found. Surely it represents one of our most photographed cricket species (208 BugGuide photos and counting).

The greatly expanded palps are thought to mimic beetle mandibles or spider pedipalps.

The greatly expanded palps are said to mimic beetle mandibles or spider pedipalps.

The obvious question to anyone who sees this species is, “Why the curiously enlarged palps?” Both males and females exhibit this character (even as juveniles), so it seems clear that there is no special sexual or hypersensory function. One idea mentioned on BugGuide (perhaps originating from this EOL post by Patrick Coin) suggests that the crickets are Batesian mimics of chemically-defended ground beetles (family Carabidae) such as bombardier beetles (genus Brachinus). This thought is based on their similar coloration, the convex and shiny (and, thus, beetle-like) forewings of the females, and some resemblance of the enlarged palpi to the mandibles of the beetles. I am not completely satisfied with this idea, since bombardier beetles are generally found on the ground rather than foliage. Moreover, males lack the convex, shiny forewings exhibited by females, and resemblance of the palps to beetle mandibles doesn’t explain their curiously constant movement (ground beetles don’t constantly move their mandibles). Another idea suggested by orthopterist (and insect macrophotographer extraordinaire!) Piotr Naskrecki is a mimetic association with another group of arthropods, noting that the busy movements of the palps is very similar to the way jumping spiders (family Salticidae) move their pedipalps. This suggestion also is not completely satisfying, as it leaves one wondering why the crickets are so boldly and conspicuously colored. While some jumping spiders are brightly colored, I’m not aware of any in eastern North America with similar coloration (indeed, many jumping spiders can be considered ‘drab’). Perhaps the crickets have adopted mimetic strategies using multiple models in their efforts to avoid predation?

The brown wings and long, sickle-shaped ovipositor identify this individual as a female.

The brown wings and sickle-shaped ovipositor identify this individual as a female.

The individual in these photos can be identified as a female due to the presence of the sickle-shaped ovipositor and, as mentioned above, the convex, shiny forewings. Males possess more typically cricket-like forewings, perhaps constrained to such shape by the sound producing function they must serve. The males do, however, exhibit an interesting dimorphism of the forewings, with one wing being clear and the other one black. Fellow St. Louisan and singing insect enthusiast James C. Trager notes this dimorphism has been mentioned in the literature but not explained and suggests it may have something to do with the adaptive physics of sound production.

Congratulations to Ben Coulter, who wins Super Crop Challenge #16, which featured a cropped close-up of the enlarged maxillary palpi of this insect. His 12 pts increase his lead in the overall standings for BitB Challenge Session #7 to an almost insurmountable 59 pts. Morgan Jackson and Troy Bartlett round out the podium with 10 and 9 pts, respectively—Troy’s points being enough to move him into 2nd place in the overalls with 23 pts. Third place in the overalls is still up for grabs, since none of the people occupying the 3rd through 6th places has played for awhile—realistically any number of people behind them could jump onto the podium (or even grab 2nd place!) in the next (and probably last) Session #7 challenge.

REFERENCE:

Capinera, J. L., R. D. Scott & T. J. Walker. 2004. Field Guide To Grasshoppers, Katydids, And Crickets Of The United States. Cornell University Press, Ithaca, New York, 249 pp. [Amazon].

© Ted C. MacRae 2014