Missouri

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

Working with Cerceris fumipennis—Epilogue

/ Ted C. MacRae / 10 Comments

Cerceris fumipennis nest littered with Neochlamisus sp. beetles

In Working with Cerceris fumipennis Part 1 and Part 2, I talked about the use of this species as a biosurveillance tool for Buprestidae. These wasps are specialist predators of jewel beetles, which they capture almost exclusively and paralyze with their sting to use as food provisions for their offspring in underground nests. I also mentioned that there are other species of Cerceris, each specializing in its own distinct prey group, and at my site in east-central Missouri I found C. bicornis, a weevil specialist, almost as common as C. fumipennis. Thus, when I came upon this particular Cerceris wasp nest, I wondered it I had encountered yet another species in the genus, for littered around it were case-bearing leaf beetles in the genus Neochlamisus.

The bright coppery coloration suggests Neochlamisus platani

I counted 11 beetles lying on the diggings surrounding this nest, and as is typical with buprestids around C. fumipennis nests these beetles all appeared to represent the same species (I’ve done a little collecting of Neochlamisus beetles in Missouri—the especially bright coppery coloration suggests to me N. platani, a species found on eastern sycamore, Platanus occidentalis). I’ve also noted that C. fumipennis nests littered with beetles on the surface also have beetles—usually of the same species—freshly cached underground, so I decided to dig up the nest to see what might be in it. As I inserted the grass stem and started digging, I heard the distinctive buzzing indicating the wasp was still inside the nest, and when it appeared I noted the distinctive three yellow facial markings that identify it as a female C. fumipennis. As suspected, the nest contained another seven beetles of the same species, and I would later learn that C. fumipennis, while specializing on jewel beetles, does occasionally take other prey. Philip Careless and colleagues recorded two leaf beetles, including Neochlamisus bebbiana, and one weevil as hosts for this wasp at their Working with Cerceris fumipennis website. If my species ID of these beetles is confirmed, this should represent yet another non-buprestid host record for C. fumipennis, although I should also mention that out of several hundred observations this was the only non-buprestid prey I observed around or in a C. fumipennis nest.

Copyright © Ted C. MacRae 2012

Working with Cerceris fumipennis—Part 2

/ Ted C. MacRae / 19 Comments

During the 6-week period from late May to early July this year, I collected ~400 jewel beetle specimens representing at least 20 species (see Working with Cerceris fumipennis—Part 1). A final accounting of the species represented won’t be done until this winter, but the genera represented include Acmaeodera, Actenodes, Agrilus, Anthaxia (Haplanthaxia), Buprestis (Knulliobuprestis), Chrysobothris, Dicerca, Poecilonota, and Spectralia. Perhaps two-thirds of the specimens were “ground-picked”¹, while most of the remaining third were “stolen” directly from wasps by netting wasps in flight as they returned to their nest carrying prey.

¹ It’s not clear to me why I found so many abandoned buprestids at nest entrances. The wasps are known to drop prey when threatened and, rather than search for and relocate the prey, fly off to look for a new beetle(Careless et al. 2009). I observed this myself in several cases when I missed netting the wasp but swiped the net close enough to scare it, at which time it dropped the beetle and flew off (and I popped the beetle in a vial). However, the bulk of the beetles I found on the ground were not only at the nest entrance, but even mixed within the diggings surrounding the nest. My first act when checking each field was to check each nest, pick up any adults lying on top of the burrow diggings, and then carefully spread out the diggings with a knife or trowel to collect the beetles hidden within them. One nest contained as many as 13 Agrlus obsoletoguttatus inside the diggings. I wondered at one point if the wasps were leaving the beetles at the burrow entrance and then digging out the burrow before coming back to retrieve them, but I never actually witnessed this. On the other hand, I observed numerous wasps approaching their burrows while carrying prey, and every time the wasp dropped directly into the burrow. In fact, I could even predict what beetle species I was likely to find inside the nest based on the species I found around the entrance (more on that below).

This ball field with contains several dozen Cerceris fumipennis nests.

There is a third method that I used to collect beetles that I haven’t yet discussed, and that is digging them out of nests. In the latter part of the survey period (late June and early July), beetle numbers dropped rapidly, as did apparent wasp activity. As mentioned in the previous post, this drop off in activity came precisely at the time of season when I have observed buprestid beetle activity to decline in Missouri. As the drop off in activity was taking place, I began wondering what I would find if I tried digging up some of the burrows. Of course, digging up a nest takes much more effort than netting wasps or picking beetles up off of the ground, so it becomes important not only to identify whether a nest actually belongs to C. fumipennis and if it is active and likely to contain freshly captured beetles.  In addition, I observed the burrows of a variety of other insects in these fields as well, some of which are shown here and which might be confused with burrow entrances of C. fumipennis.

Cerceris fumipennis nest with Chrysobothris sp. adult left on diggings.

Cerceris fumipennis burrows exhibit perfectly circular, pencil-sized entrances surrounded by a symmetrical mound of diggings with a fine rather than granular texture. There are other Cerceris species that make nearly identical burrows, but they prey on other insects rather than buprestid beetles. At my site I found C. bicornis, a weevil specialist, almost as common as C. fumipennis. Their burrow entrances on the whole seemed slightly larger, but I could not use this as consistent distinguishing character. What I could use, however, was the presence of weevils rather than buprestids lying on the ground near the nest entrance. (I also observed this species returning to its nest and noted a rather faster, more powerful flight that made them even more difficult to capture than C. fumipennis). In contrast, there can be no doubt that the burrow above, with a buprestid beetle lying on the ground near the entrance, belongs to C. fumipennis.²

² The white plastic tag marks the burrow to facilitate locating nests on subsequent visits. It is secured with a golf tee and also can be rotated so that the hole covers the entrance. The hole is large enough to allow the wasp to leave but too small for a returning wasp to enter while carrying a beetle. The idea was to rotate the tags when I first entered a field to cover all the burrow entrances, watch for wasps returning with prey, and then net the wasps as they tried (in vain) to enter the burrow. However, I never actually observed a wasp trying to enter a covered burrow, even after leaving a field and returning 20–30 minutes later.

I presume this nest to be that of Bembix americana (sand wasp).

For the first few weeks, I thought the burrows such as that shown in the above photo also belonged to C. fumipennis. However, I never found beetles lying on the ground near the entrance, nor did I ever observe a wasp to enter or leave the burrow. I eventually noticed several distinct differences in burrow architecture—the burrow entered the ground at an angle rather than straight down, the diggings were distributed asymmetrically to one side of the entrance, and the latter seemed consistently a little larger than those of C. fumipennis. In addition, these burrows always seemed to be in the sandier portions of the fields. While I never associated any insect directly with these burrows, I did observe sand wasps (perhaps Bembix americana) in the vicinity and have seen similar-looking burrows dug by these wasps at Sand Prairie Conservation Area.

Larval burrows of Cicindelidia punctulata and other tiger beetles lack diggings around the entrance.

Tiger beetle larval burrows might also be confused with C. fumipennis burrows, especially after rain or high winds which can wash/blow away the diggings from around the entrance. I found adults of the punctured tiger beetle, Cicindelidia punctulata, fairly commonly at the site and presume the numerous tiger beetle larval burrows that were also present belong to that species. Larval tiger beetles burrows also enter the ground straight down and are, at first appearance, also perfectly round, but they are usually a little too small for C. fumipennis (those of Tetracha spp. being an exception)—the presumed C. punctulata burrow in the above photo measures about 5 mm in diameter. In addition, closer examination reveals a slight “D” shape to the burrow entrance (upper right in the above photo—the tiger beetle larva rests its jaws against the flat side) and, more distinctively, beveling of the ground around the rim of the burrow entrance. Cerceris fumipennis nests lack the slight D-shape and distinctive beveling.

Use a grass stem as a guide while carefully digging away the surrounding soil.

Years of practice digging up tiger beetle burrows prepared me well for my first attempts at digging up C. fumipennis burrows. While it might seem an easy task to follow a hole into the ground while digging soil away from it, in practice the burrow can be quickly lost after even a few inches due to falling soil covering the hole and making it impossible to relocate. I use a thin, flexible but sturdy grass stem to preserve the burrow path, inserting the stem into the burrow and down as far as it will go and then removing the soil carefully from around the hole with a knife or trowel. I try to avoid letting soil fall over the hole by prying the soil away from the hole, but if the hole does get covered the grass stem allows it to be easily relocated.

This nest contained a single Buprestis rufipes…

Cerceris fumipennis burrows are not very deep—only 10–15 cm, and angle to one side a few cm below the surface before leveling out near the bottom. I noticed the nest in the above photo because I saw a wasp fly into it. When I went over to look at it I found a Buprestis rufipes lying on the ground near the entrance and so decided to dig it up. As I expected, I found another B. rufipes at the bottom of the burrow (two above photos courtesy of Madison MacRae).

…while this one contained a cache of seven Agrilus quadriguttatus.

The above photo shows a cache of seven Agrilus quadriguttatus that I found at the bottom of another burrow. In this case, the prey is rather small compared to large prey such as Buprestis and Dicerca. While nests provisioned with species in these latter genera often contained only a single beetle in them, I nearly always found multiple beetles in nests provisioned with the smaller Agrilus species. One nest contained as many as 13 Agrilus obsoletoguttatus, among the smallest of the species I found utilized by C. fumipennis at this site.

Buprestidae taken from five different Cerceris fumipennis nests.

Some of the nests I dug up contained multiple species of beetles, but far more commonly I found only a single species in a given nest. The photo above shows the diversity and number of beetles found on one date after digging up five different nests. From top left the beetles are: 1) 1 Buprestis rufipes; 2) 2 Agrilus quadriguttatus and 1 A. obsoletoguttatus; 3) 2 A. quadriguttatus and 1 A. obsoletoguttatus; 4) 8 A. obsoletoguttatus; and 5) 2 Poecilonota cyanipes, 2 A. quadriguttatus, and 1 A. pseudofallax. It would make sense for wasps to provision nests with greater numbers of smaller beetles to ensure adequate food for their larvae to complete development. How the wasps actually locate their prey, and why this species has specialized almost exclusively on buprestid beetles, is a mystery (at least to me); however (and here comes the speculation du jour), I suspect the wasps may have keyed in on volatiles used by the beetles—either those released by suitable hosts or by each other to facilitate mate location. Use of buprestid pheromones or freshly dead host volatiles would allow wasps to more efficiently locate buprestid prey and, once locating a source (a tree harboring a particular beetle species), could return repeatedly to provision their nest fully. It seems less likely that wasps rely exclusively on visual location of prey, as this would involve a large amount of random searching through trees and passing up numerous, seemingly equally suitable prey.

REFERENCE:

Careless, P. D., S. A. Marshal, B. D. Gill, E. Appleton, R, Favrin & T. Kimoto. 2009. Cerceris fumipennis—a biosurveillance tool for emerald ash borer. Canadian Food Inspection Agency, 16 pp.

Copyright © Ted C. MacRae 2012

Working with Cerceris fumipennis—Part 1

/ Ted C. MacRae / 20 Comments

For nearly 30 years, jewel beetles (family Buprestidae) have been my primary research interest. While some species in this family have long been regarded as forest and landscape pests, my interest in the group has a more biosystematic focus. A faunal survey of Missouri was the result of my initial efforts (MacRae 1991), while later research has focused on distributions and larval host associations of North American species (Nelson & MacRae 1990; Nelson et al. 1996; MacRae & Nelson 2003; MacRae 2004, 2006) and descriptions of new species from both North America (Nelson & MacRae 1994, MacRae 2003b) and South America (MacRae 2003a). Research interest in other groups—especially longhorned beetles and tiger beetles, has come and gone over the past three decades; however, I always return to jewel beetles as  my first and favorite group.

In recent years, one species in particular—the emerald ash borer (EAB, Agrilus planipennis) has garnered a huge amount of research, regulatory, and public interest after reaching North America from Asia and spreading alarmingly through the hardwood forests of Michigan and surrounding states. The attention is justifiable, given the waves of dead native ash trees that have been left in its wake. With huge areas in eastern North America still potentially vulnerable to invasion by this species, the bulk of the attention has focused on preventing its spread from infested areas and monitoring areas outside of its known current distribution to detect invasion as early as possible. One incredibly useful tool that has been adopted by survey entomologists is the crabronid wasp, Cerceris fumipennis. Like other members of the family, these solitary wasps dig nests in the ground, which they then provision with captured insect prey. The wasp uses its sting to paralyzed the prey but not kill it, and once inside the burrow the wasp lays an egg on the prey and seals the cell with a plug of soil. The eggs hatch and larvae develop by consuming the paralyzed prey (unable to scream!). After pupation the adult digs its way out of the burrow (usually the next season), and the cycle begins anew. However, unlike other members of the family (at least in North America), C. fumipennis specializes almost exclusively on jewel beetles for prey. So efficient are these wasps at locating and capturing the beetles that entomologists have begun using them to sample areas around known wasp populations as a means of detecting the presence of EAB. Philip Careless and Stephen Marshall (University of Guelph, Ontario) and colleagues have been leading this charge and have even developed methods for transporting wasp colonies as a mobile survey tool and developed a sizeable network of citizen scientists throughout eastern North America to expand the scope of their survey efforts. Information about this can be found at the excellent website, Working with Cerceris fumipennis (please pardon my shameless lifting of the title for this post).

I first became aware of the potential of working with C. fumipennis a few years ago when Philip sent me a PDF of his recently published brochure on use of this wasp for EAB biosurveillance (Careless et al. 2009). My correspondence with him and other eastern entomologists involved in the work suggested that ball fields with lightly vegetated, sandy soil would be the best places to look for C. fumipennis nests, but my cursory attempts to find the wasp at that time were unsuccessful. I reasoned that the clay-soaked soils of Missouri didn’t offer enough sand for the wasps’ liking and didn’t think much more about it until last winter when I agreed to receive for ID a batch of 500+ buprestid specimens taken from C. fumipennis wasps in Louisiana. What a batch of material! In addition to nice series of several species that I had rarely or never seen (e.g. Poecilonota thureura), three new state records were represented amongst the material. A paper is now in progress based on these collections, and that experience catalyzed a more concerted effort on my part to locate a population of the wasp in Missouri. Museum specimens were no help—the only records from Missouri were from old specimens bearing generic locality labels such as “St. Louis” and “Columbia.” Throughout the month of May, I visited as many ball fields as I could, but the results were always the same—regularly groomed, heavy clay, barren soil with no evidence of wasp burrows (or any burrows for that matter).

Near the end of May, however, I had a stroke of luck. I had switched to a flatter route through the Missouri River Valley to ride my bike to work because of knee pain (now thankfully gone) when I saw this:

Practice fields at Chesterfield Valley Athletic Complex | St. Louis Co., Missouri

Those are “practice” fields in front of regular fields in the background, and unlike the latter, this row of nine fields (lined up against the levee adjacent to the Big Muddy National Wildlife Refuge) showed no evidence of regular grooming or heavy human use. Only ten miles from my home, I made immediate plans to inspect the site at the first opportunity that weekend. Within minutes after walking onto the lightly vegetated, sandy-clay soil of the first field, I found numerous burrows such as this:

Cerceris fumipennis with circular, pencil-wide burrow entrance and symmetrical mound of diggings.

Only a few more minutes passed before I found an occupied nest, the wasp sitting just about an inch below the entrance to its pencil-wide burrow. The three yellow markings on the face indicated it was a female (males have only two facial markings), and in short order I found numerous other burrows also occupied by female wasps. Some were just sitting below the burrow entrance, while others were actively digging and pushing soil out of the burrow with their abdomen. I flicked a little bit of soil into one of the burrows with a female sitting below the surface, which prompted an immediate “cleaning out” of the burrow—this explains the dirty face of the female in the following photo, but the three yellow facial markings are clearly visible:

Cerceris fumipennis female removing soil from burrow entrance.

After finding the burrows and their occupants, I began to notice a fair number of wasps in flight—leaving nests, returning to nests, and flying about as if searching for a ‘misplaced’ nest. A few of these were males, but most were females, and I also caught a couple pairs flying in copula (or at least hitched, if not actually copulating). Despite the number of wasps observed during this first visit, I didn’t see a single wasp carrying a buprestid beetle. This puzzled me, because all of the Louisiana beetles I had determined last winter were taken by standing in the midst of nests and netting those observed carrying beetles. Finally, I had confirmation that I was truly dealing with this species when I found a couple of beetles lying on the ground near the entrance to a burrow. These would be the only beetles that I would find on this visit, but subsequent visits during the following few weeks would show “ground picking” to be the most productive method of collecting beetles. Across the nine fields, I found a total of nearly 300 nests, and the wasps showed a clear preference for some fields over others—one field (P-6) had about 150 nests, while a few others had less than a dozen. The photo shown in ID Challenge #19 shows a sampling of ground-picked buprestids from P-6 in a single day, and occasionally I would find a real prize like Buprestis rufipes:

Buprestis rufipes laying near Cerceris fumipennis nest entrance.

Coincident with the appearance of large numbers of beetles laying on the ground near nest entrances, I also began to see wasps carrying their prey. Wasps carrying large beetles are easily recognized by their profile, but even those carrying small beetles look a little more “thick-thoraxed” (they hold their prey upside down and head forward under their thorax) and exhibit a slower, more straight-line flight path compared to the faster, more erratic and repetitively dipping flight of wasps not carrying prey. Learning how to discern wasps carrying prey in flight from the more numerous empty-handed wasps prevents a lot of wasted time and effort netting the latter. Nevertheless, there does appear to be some bias towards larger beetles when netting prey-carrying wasps in flight, as evidenced in the photo below of beetles taken by this method, also in field P-6, on the same date as the ground-picked beetles shown in ID Challenge #19. This could be a result of visual bias towards wasps carrying larger beetles, as in later visits (and presumably with a more refined search image) I did succeed in catching larger numbers wasps carrying smaller beetles (primarily in the genus Agrilus).

Buprestid prey of Cerceris fumipennis: L–R and top to bottom 2 Dicerca obscura, 2 D. lurida, 3 Poecilonota cyanipes, 2 Acetenodes acornis, 1 Chrysobothris sexsignata, 1 Agrilus quadriguttatus, and 1 A. obsoletoguttatus

All told, I collected several hundred beetles during my twice weekly visits to the site from late May to the end of June. Beetle abundance and wasp activity began to drop off precipitously in late June, which coincides precisely with the end of the adult activity period for a majority of buprestid beetles in Missouri, based on my observations over the years. This did not, however, spell the end of my activities in using C. fumipennis to collect buprestid beetles, which will be the subject of Part 2 in this series.

Congratulations to Joshua Basham, whose efforts in ID Challenge #19 earned him 12 points and the win. Morgan Jackson and Paul Kaufman were the only others to correctly identify the Cerceris fumipennis connection and take 2nd and 3rd, respectively. In an unexpected turn of events, BitB Challenge Session #6 overall leader Sam Heads did not participate and was leapfrogged by Brady Richards, whose becomes the new overall leader with 59 points. Sam now trails Brady by 5 points, while Mr. Phidippus lies another 3 points back. With margins this tight, the overall standing can still change in a single challenge, and there will be at least one more in this current session before an overall winner is named.

REFERENCES:

Careless, P. D., S. A. Marshal, B. D. Gill, E. Appleton, R, Favrin & T. Kimoto. 2009. Cerceris fumipennis—a biosurveillance tool for emerald ash borer. Canadian Food Inspection Agency, 16 pp.

MacRae, T. C. 1991. The Buprestidae (Coleoptera) of Missouri. Insecta Mundi 5(2):101–126.

MacRae, T. C. 2003a. Mastogenius guayllabambensis MacRae, a new species from Ecuador (Coleoptera: Buprestidae: Haplostethini). The Coleopterists Bulletin 57(2):149–153.

MacRae, T. C. 2003b. 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.

MacRae, T. C. 2004. Notes on host associations of Taphrocerus gracilis (Say) (Coleoptera: Buprestidae) and its life history in Missouri. The Coleopterists Bulletin 58(3):388–390.

MacRae, T. C. 2006. Distributional and biological notes on North American Buprestidae (Coleoptera), with comments on variation in Anthaxia (Haplanthaxia) viridicornis (Say) and A. (H.) viridfrons Gory. The Pan-Pacific Entomologist 82(2):166–199.

MacRae, T. C., & G. H. Nelson. 2003. Distributional and biological notes on Buprestidae (Coleoptera) in North and Central America and the West Indies, with validation of one species. The Coleopterists Bulletin 57(1):57–70.

Nelson, G. H., & T. C. MacRae. 1990. Additional notes on the biology and distribution of Buprestidae (Coleoptera) in North America, III. The Coleopterists Bulletin 44(3):349–354.

Nelson, G. H., & T. C. MacRae. 1994. Oaxacanthaxia nigroaenea Nelson and MacRae, a new species from Mexico (Coleoptera: Buprestidae). The Coleopterists Bulletin 48(2):149–152.

Nelson, G. H., R. L. Westcott & T. C. MacRae. 1996. Miscellaneous notes on Buprestidae and Schizopodidae occurring in the United States and Canada, including descriptions of previously unknown sexes of six Agrilus Curtis (Coleoptera). The Coleopterists Bulletin 50(2):183–191.

Copyright © Ted C. MacRae 2012

The importance of background and apparent light size

/ Ted C. MacRae / 8 Comments

I’m still getting submissions for ID Challenge #19 and don’t quite have the followup post ready yet, so I’ll give it a couple more days. In the meantime, I’d like to re-share the photo below, originally shown a few weeks ago in my post  A few people commented that this was their favorite photo in the series—perhaps like me they are suckers for face shots, but I think this photo succeeds in large part because of its soft-green background. This was actually one of several similar face shots that I took, each differing the other almost exclusively in the choice of background. In the end, I chose the green background to include in the post, not only because it was the most aesthetically pleasing, but also because I felt it best represented the environment of the beetle—ensconced within the foliage of its preferred host plant, ninebark (Physocarpus opulifolius).

Green background—achieved by placing a leaf some distance behind the subject.

Such background is easily achieved in full-flash macro photography by placing a green leaf some distance behind the subject, although in practice this can be a little tricky—you want the leaf far enough away from the subject that it is completely out of focus, eliminating distracting details, but close enough so that it actually reflects light from the flash and shows up as green. This becomes trickier still if the photographer is already holding the subject (as I was, or at least the branch on which the subject was sitting), as the distance between the subject and the background must be adjusted by moving the subject (and hence the camera), rather than the leaf.

Black background—the typical background of full-flash macrophotography.

Here is a similar shot of the beetle without placing anything in the background. This is full-flash lighting because I’m using small apertures and high shutter speeds to prevent motion blur and maximize depth-of-field. As a result, only objects in the vicinity of the subject and illuminated by the flash will show up in the exposure. This results in the almost-trademark black background of typical full-flash illuminated macrophotography. Despite what you may read or hear, there is nothing wrong with a black background. Some consider it boring—probably because it is so common in macrophotography. However, there are times when it truly is the best choice of backgrounds—especially with a white or light-colored subject (for example, see this photo of the white-flowered Great Plains ladies’-tresses orchid, Spiranthes magnicamporum). With darker subjects, however, black may not be the most appealing choice of backgrounds, so it’s good to keep this in mind and choose accordingly.

Blue background—bump the ISO up to 320 and point the subject to the brightest part of the sky.

Of course, there is one way to avoid a black background without placing an object behind the subject (or placing the subject in front of an object), and that is to use the open sky to achieve a nice, blue background. This is one of the trickier of the background techniques, as it relies on finding a fine balance between ISO, aperture and shutter speed. For this photo, I bumped the ISO up to 320 (normally I use 160) and slightly opened up the aperture (f/13 rather than f/16). These settings, combined with pointing the subject to the very brightest part of the sky (excluding the sun!) allowed me to keep the shutter speed reasonably fast (1/200 sec). I find that lower shutter speeds nearly always result in some motion blur (all of my photos are hand-held), so I avoid reducing shutter speed if at all possible. I also find that ISO settings above 320 result in unacceptable graininess, so I will back down on the aperture (even down to f/11 or f/10) if I have to in order to avoid going above ISO 320 and below 1/200 sec exposure. On especially bright days, areas of the sky closest to the sun will provide enough light that you can use aperture to fine-tune the background to the desired intensity of blue—the smaller the aperture the more intense and darker the blue will be (along with providing greater depth of field). While a blue background works for this subject, I simply like the green background better. I find that blue background shots are most pleasing with foliage and flower-feeding insects, adding a touch of realism to the photo without the cluttered, distracting look of other natural backgrounds or the “studio” feel of black background shots. This photo of the South American weevil, Megabaris quadriguttatus, is perhaps my favorite example of the use of blue background.

By now, the more technically oriented photographer types among you might have noticed something that all three photos have in common (besides the subject), and that is the difference in specular highlighting exhibited by the left and right eyes of the subject. Reverse engineering suggests that I had two sources of light (which is true, I use Canon’s MT24-EX twin macro flash), and that the light source illuminating the beetle’s right side either had a much larger diffuser or was placed much closer to the subject. In fact, it was the latter, as I simply detached the left flash unit and held it much closer to the subject to confirm for myself what effect this has. Because the flash unit is closer to the subject, it has much larger apparent size, resulting in more even lighting over that side of the subject and, accordingly, softer specular highlights. If I had a third arm I would have done the same with the second light source (and a fourth arm would allow me to also hold a green leaf behind the subject!). Unfortunately, additional appendages are not an option, so I’m going to have to figure out an efficient, light, easy way to get my light sources as close to the subject as possible. Snoot diffusers are one option, but they have limited flexibility to make fine adjustments to the subject-distance as camera distance changes. Going to a single light source and holding it off-camera is another option, but hand-holding a light source leaves one less hand to hold other things (like the subject), and I do prefer the reduction of shadows provided by multiple light sources. I’ve already discussed the , and I do have some other ideas that I’m working on as well. However, your ideas also would be most welcome!

Copyright © Ted C. MacRae 2012

ID Challenge #19

/ Ted C. MacRae / 33 Comments

We all have something in common…

Here is a bit of a different ID Challenge—can you identify the beetles represented in the photo, but more importantly can you deduce what all of these beetles have in common (other than the fact that they belong to the same family)? Obviously these are all jewel beetles (family Buprestidae), so we won’t worry about higher classification. Instead, I’ll give 1 pt for each correctly named genus (don’t bother trying to identify species) and a whopping 5 pts for figuring out what it is they have in common. Early bird pts will be given for the latter question only. Please read the full rules if you are not already familiar with them—good luck!

Copyright © Ted C. MacRae 2012

More on Chalcosyrphus

/ Ted C. MacRae / 2 Comments

Here are two more photos of the fly I tentatively identified as Chalcosyrphus sp. The first photo shows the all-black coloration with no trace of either steel blue highlights (seen in C. chalybea) or red abdominal markings (seen in C. piger). It also gives a better view of the enlarged and ventrally spinose metafemora. The second photo shows the holoptic (contiguous) eyes that make me think this is a male individual (if, indeed, this is true for syrphids as with tabanids).

I’m hoping that posting these will provide any passing dipterists with the information needed for a firmer ID (and possibly an explanation of the purpose of those intriguingly modified hind legs).

Lateral view showing black abdomen with no trace of red (except what appears to be a parasitic mite).

Do the holoptic eyes identify this as a male?

Copyright © Ted C. MacRae 2012

T.G.I.Flyday – Chalcosyrphus?

/ Ted C. MacRae / 5 Comments

When I was an entomology student, I learned that flies in the family Syrphidae are called “hover flies,” due to their habit of hovering in front of flowers, and that the larvae are predators of aphids. As is the case for nearly every other group of insects, I now know that there are exceptions–often many—to the typical rule, and the fly shown in the above photograph is a perfect example of such. Being a beetle-man (and a wood-boring beetle-man, at that), I don’t generally notice flies unless there is something unusual about them. This fly was seen last summer at Sam A. Baker State Park in southeastern Missouri on the trunk of a very large, recently wind-thrown mockernut hickory (Carya alba) tree. I had never seen a fly quite like this before, but everything about it suggested an intimate association with dead wood, including its relatively large, hulking, black form and the way it repeated returned to and landed on the trunk of the dead tree each time I disturbed it. It instantly made me think of robber flies in the subfamily Laphriinae, which includes Andrenosoma fulvicaudum and many species of Laphria that, as larvae, tunnel through dead and decaying wood where they prey upon the larvae of wood-boring beetles. While it was quite obvious that the fly in the photo was not a robber fly, imagine my surprise when I eventually determined it to be a member of the family Syrphidae. For now I’ve provisionally settled on the genus Chalcosyrphus, although it lacks the steely blue cast exhibited by the only all-black species of the genus—C. chalybeus—shown on BugGuide. Another species, C. piger, looks very similar but seems always to have some red on the abdomen, which this individual definitely lacks. Perhaps the related genus Xylota is also a possibility, although the “gestalt” does not seem to quite match that of any shown on BugGuide. Most interesting for me are the distinctly enlarged and toothed metafemora, which along with the correspondingly curved tibiae suggest some predatory function, but the literature that I have seen makes no mention of such, but rather that the adults feed on pollen. My hunch about its association with dead wood does seem to be true, although it now seems the larvae are saprophages rather than predators within the wood, as I first imagined.

Copyright © Ted C. MacRae 2012