Digger wasps in action

Bicyrtes quadrifasciatus

Bicyrtes quadrifasciatus digging a burrow | Stoddard Co., Missouri

Here is an animated gif that I made from a series of photographs of the digger wasp, Bicyrtes quadrifasciatus (ID courtesy of Doug Yanega), digging a burrow in a sand bank in extreme southeastern Missouri (it’s amazing what you can do with an iPhone and a free internet app!). A large number of these wasps had colonized the sand bank, and as I photographed this one individual busily digging its burrow, others repeatedly flew up and investigated. The digging individual would disappear briefly down into the burrow, and each time it returned to the surface with a fresh load of sand another wasp would fly up to it and investigate. The digging individual never seemed to pay much attention to the investigating wasp, so I’m not sure if these other wasps were looking for a potential mate or perhaps even trying to usurp the burrow.

The cumulative noise from all of the flying wasps was really quite remarkable—indeed, the noise is what drew my attention to the sand bank in the first place. A video of the colony with my commentary can be seen here. I did see one wasp that had returned to its burrow carrying prey (apparently a stink bug in the family Pentatomidae). I touched the wasp thinking that it would drop the prey and fly away, as another digger wasp, Cerceris fumipennis, does with its buprestid prey when disturbed. This would have given me a chance to confirm the prey identity. Unfortunately, the wasp kept hold of the prey and flew off with it.

© Ted C. MacRae 2014

Brazilian Bike Adventure

Atlantic Forest

Atlantic Forest in Serra do Mar.

Yesterday I joined my Brazilian colleagues on a bicycling tour from the outskirts of São Paulo to the beaches of the Atlantic Coast. To say that the tour was an ‘adventure’ is an understatement—it was epic! For those not familiar with São Paulo, its 20 million inhabitants make it not only the largest city in Brazil, but also one of the five largest cities in the world. Yet, despite the explosive growth it has seen during the past century, it remains isolated from the Atlantic Coast of southeastern Brazil by the Serra do Mar, a 40-kilometer wide swath of rugged, mountainous terrain and part of the Great Escarpment that runs along much of the eastern coast of Brazil. It is here where some of the last tracts of Atlantic Forest, the second largest forest ecotype in South America after the Amazon, remain. Atlantic Forest once stretched along much of Brazil’s Atlantic coast, turning inland in its southern reaches to Paraguay and the northern tip of Argentina. However, much of the forest, especially in populous southeastern Brazil, has fallen victim to the axe. Only the ruggedness of the Serra do Mar has allowed the Atlantic Forest to survive in such close proximity to one of the world’s most populous cities. Understandably, travel between São Paulo and the coast has been difficult. In former years, vehicles had to snake their way through the mountains along a treacherous 2-lane highway with steep grades and hairpin turns. That highway has since been circumvented by an elevated, double, 4-lane highway of alternating spans and tunnels, and the old highway, now closed to vehicles, is instead used by maintenance crews for the new highway and cyclists who yearn to experience the Atlantic Forest up close and personal.

Our van dropped us off in the outskirts of São Paulo, from where we rode along the main highway a short bit before accessing the old highway. Dropping into the Atlantic Forest was like being magically transported into virgin wilderness. The pavement was so encroached by the forest, steep and slippery in places, that it was hard to imagine it ever served as a link between Brazil’s largest city and its largest port. Heavy rains the previous night made the forest moist and gave it an earthy aroma, and moisture-laden air hung heavy with fog and intermittent drizzle. For a time it seemed we would have an uninterrupted, 40-km downhill freeride; however, just a few kilometers into the ride we encountered the first of what would be many landslides blocking the route. I can honestly say that I’ve never portaged a bike through as rough and tumble a pile of trees, rocks, and mud as I did on this day. Still, perhaps encouraged by the fresh bike tracks that lay before us, we soldiered on. After picking our way through a half-dozen such landslides we came upon a work crew who said there were another 30–40 landslides further down along the route. We were at a tunnel that connected with the main highway, so we decided to play it safe and take the main highway the rest of the way down. That, too, was an adventure, made feasible only by the fact that traffic was crawling at a snail’s pace due to the popularity of the Atlantic beaches with the citizenry of São Paulo. It was enjoyable to swish past the cars as they idled their engines, but we had to navigate about seven kilometers worth of shoulderless tunnels. That would have been impossible in normal traffic, but the congestion made finding room to squeeze by large trucks and buses the biggest problem (and I guess breathing exhaust!). Eventually we made it down into Santos, the largest port city in Brazil, and after picking our way through the center of the city, took a ferry to the beach city of Guarujá. Rain, landslides and traffic had thrown everything they had at us, but we persevered the 53-km trek and watched the sun break through while enjoying our just rewards in a beachside restaurant.

Following are a few more of my favorite photos from the day, and you can see all of them in my Facebook album Brazilian Bike Adventure.

Descending into the forest.

Descending into the forest.

Magical vistas such as this were around every turn of the road.

Magical vistas such as this awaited us around every turn of the road.

Manacá da Serra (Tibouchina mutabilis) was abundant in the forest.

Manacá da Serra (Tibouchina mutabilis) flowered in abundance in the forest.

Elevated roadways bypass the beauty of the forest below them.

Why did the ‘hellgramite’ (order Megaloptera, family Corydalidae) cross the road? (Thanks to dragonflywoman for the ID.)

The first of many landslides that blocked our path.

The first of many landslides that blocked our path.

The new elevated highway snakes through the Serra do Mar. This portion was closed due to landslides.

The new elevated highway snakes through the Serra do Mar. This portion was closed due to landslides.

Outside of the cicada killer, this digger wasp (family Crabronidae) on the  beach at Guarujá is the largest that I have ever seen.

A large digger wasp (family Crabronidae) greets us on the beach at Guarujá.

My Brazilian colleagues and I enjoy some well-deserved refreshments after our 53-km trek!

My Brazilian colleagues and I enjoy some well-deserved refreshments after our 53-km trek!

I may have looked like a nerd still in my cycling clothes, but the wave experience was unforgettable.

I may have looked like a nerd still in my cycling clothes, but the wave experience was unforgettable.

Copyright © Ted C. MacRae 2013

Working with Cerceris fumipennis—Epilogue

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

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 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

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

Cicada killer on the fly

An eastern cicada killer (Sphecius speciosus) searches for her burrow | Jacksonville, Illinois.

I don’t normally spend much time trying to photograph insects in flight. To really do it right requires some rather specialized equipment, including very high-speed flash, and a bucketload of patience and skill. John Abbott exemplifies those whose great talent has produced stunning photographs of insects in mid-flight. That’s not to say that it can’t be done “on the fly,” so to speak, and even a hack like me can get lucky every now and then.

Earlier today I found a rather large number of eastern cicada killers (Sphecius speciosus) in a ball field in Jacksonville, Illinois. These impressive wasps are the largest wasp in eastern North America and have the rather gruesome habit of paralyzing cicadas with their sting, and then dragging them down into their burrows to be eaten alive by their grubs. I’ve recently become interested in solitary wasps (for reasons to be discussed later) and decided to see if I could get some decent photographs. I got a few I like (more on this later), but my favorite is this total luck-out shot of a wasp face-on in mid-flight. As I watched them, I noticed that each wasp spent a fair amount of time trying to identify its burrow amongst the dozen or more that were clustered along one side of the field. Occasionally they would land and search about a bit on foot, then take wing again to continue their search. I decided the best way to get a shot of one on the wing would be to watch for a wasp to arrive and begin its search. When I spotted one I would slowly close distance so I could be ready to get down on my elbows as soon as it landed (closing distance without spooking the wasp was not easy). I had just my center focal point set and autofocus turned on (normally I don’t use autofocus) and had already worked out a good flash exposure compensation setting. As soon as I got on my elbows, I would quickly frame the wasp and repeatedly trigger the autofocus as I got even closer, and when the wasp took flight I took the shot. This was still a crap shoot—I ended up with lots of out-of-focus and out-of-frame photos. Nevertheless, a few turned out fairly decent, one of which was this single, perfectly head-on and well-focused photo (though admittedly somewhat cropped).

Too bad I didn’t collect any of the wasps—at $49 each I could’ve made enough cash to buy that flash bracket I’ve been eyeing!

Copyright © Ted C. MacRae 2012

A sand prairie autumn

Splitbeard bluestem seed headsAsk any astronomer when autumn begins, and they will likely tell you it begins at the autumnal equinox – when shortening days and lengthening nights become equal as the sun crosses over the celestial equator. According to them, fall began this year on September 22 – at 11:44:18 A.M. EDT, to be precise. I agree that autumn begins at a precise moment, but it is not at the equinox. Rather, it is that unpredictable moment when a sudden crispness in the air is felt, when the sky somehow seems bluer and shadows seem sharper, and hints of yellow – ever so subtle – start to appear in the landscape. Butterfly pea blossomIn Missouri, with its middle latitudes, this usually happens a few weeks before the equinox, as August is waning into September. It is a moment that goes unnoticed by many, especially those whose lives and livelihoods have lost all connection with the natural world. To plants and animals, however, it is a clear signal – a signal to begin making preparations for the long cold months of winter that lie ahead. Plants that have not yet flowered begin to do so in earnest, while those that have shift energy reserves into developing seeds. Animals take advantage of their final opportunities to feed before enduring the scarcities of winter, digging in to sleep through them, or abandoning altogether and migrating to warmer climes. Insects begin hastily provisioning nests for their broods or laying eggs – tiny capsules of life that survive the harsh winter before hatching in spring and beginning the cycle anew.

Sand prairie in early September.Sand prairie in early October.  Note abundance of splitbeard bluestem seed heads.Across much of Missouri, in the Ozark Highlands and in riparian ribbons dissecting the northern Plains, autumn brings an increasingly intense display of reds, purples, oranges, and yellows, as the leaves of deciduous hardwoods begin breaking down their chlorophyll to unmask underlying anthocyanins and other pigments. Small southern jointweedIn Missouri’s remnant prairies, seas of verdant green morph to muted shades of amber, tawny, and beige. This subtle transformation is even more spectacular in the critically imperiled sand prairies of the Southeast Lowlands, where stands of splitbeard bluestem (Andropogon ternaries – above) turn a rich russet color while fluffy, white seed heads (1st paragraph, 1st photo) appear along the length of each stem, evoking images of shooting fireworks. Small southern jointweed (Polygonella americana – right) finds a home at the northern extent of its distribution in these prairie remnants and in similar habitats in nearby Crowley’s Ridge, blooming in profusion once the cooler nights arrive. Butterfly pea (Clitoria mariana – 1st paragraph, 2nd photo) blooms add a gorgeous splash of soft purple in contrast to the muted colors of the plants around them.

Kent Fothergill, Ted MacRae, and Rich ThomaAfter first becoming acquainted with Missouri’s sand prairies this past summer, I knew a fall trip (or two) would be in order. The extensive deep, dry sand barrens were ideal habitat for sand-loving insects, including certain spring/fall species of tiger beetles that would not be active during the summer months. The cooler nights and crisp air of early fall make insect collecting extraordinarily pleasurable, so it took little effort to convince friends and colleagues Kent and Rich to join me on another excursion to these extraordinary remnant habitats, along with my (then 8 yr-old) daughter Madison (who would likely characterize this as “tallgrass” prairie). Madison MacRae, age 9 (almost)I was, as ever, on the lookout for tiger beetles; however, temperatures were cool, skies were overcast, and the fall season was just beginning, greatly limiting tiger beetle activity during this first fall visit. We did see one Cicindela formosa (big sand tiger beetle), which cooperated fully for a nice series of photographs. We also found single specimens of the annoyingly ubiquitous C. punctulata (punctured tiger beetle) and a curiously out-of-place C. duodecimguttata (12-spotted tiger beetle), which must have flown some distance from the nearest dark, muddy streambank that it surely prefers. Of greatest interest, we found two specimens of C. scutellaris (festive tiger beetle), which in this part of Missouri is represented by a population presenting a curious mix of influences from two different subspecies (more on this in a later post…). Despite the scarcity of tiger beetles, other insects were present in great diversity, some of which I share with you here.

Ululodes macleayanusThis bizarre creature, sitting on the stem of plains snakecotton (Froelichia floridana), is actually a neuropteran insect called an owlfly (family Ascalaphidae). Looking like a cross between a dragonfly and a butterfly due to its overly large eyes and many-veined wings but with long, clubbed antennae, this individual is demonstrating the cryptic resting posture they often assume with the abdomen projecting from the perch and resembling a twig. The divided eyes identify this individual as belonging to the genus Ululodes, and Dr. John D. Oswald (Texas A&M University) has kindly identified the species as U. macleayanus. As is true of many groups of insects, their taxonomy is far from completely understood. Larvae of these basal holometabolans are predaceous, lying on the ground with their large trap-jaws held wide open and often camouflaging themselves with sand and debris while waiting for prey. The slightest contact with the jaws springs them shut, and within a few minutes the prey is paralyzed and can be sucked dry at the larva’s leisure.

Ant lion, possibly in the genus Myrmeleon.Another family of neuropteran insects closely related to owlflies are antlions (family Myrmeleontidae, sometimes misspelled “Myrmeleonidae”). This individual (resting lower down on the very same F. floridana stem) may be in the genus Myrmeleon, but my wanting expertise doesn’t allow a more conclusive identification [edit 4/12/09 – John D. Oswald has identified the species as Myrmeleon immaculatus]. Strictly speaking, the term “antlion” applies to the larval form of the members of this family, all of whom create pits in sandy soils to trap ants and other small insects, thus, it’s occurrence in the sand prairie is not surprising. Larvae lie in wait beneath the sand at the bottom of the pit, flipping sand on the hapless prey to prevent it from escaping until they can impale it with their large, sickle-shaped jaws, inject digestive enzymes that ‘pre-digest’ the prey’s tissues, and suck out the liquifying contents. Finding larvae is not easy – even when pits are located and dug up, the larvae lie motionless and are often covered with a layer of sand that makes them almost impossible to detect. I’ve tried digging up pits several times and have failed as yet to find one. Larvae are also sometimes referred to as “doodlebugs” in reference to the winding, spiralling trails that the larvae leave in the sand while searching for a good trap location – these trails look like someone has doodled in the sand.

Bembix americanaThis digger wasp, Bembix americana (ID confirmed by Matthias Buck), was common on the barren sand exposures, where they dig burrows into the loose sand. Formerly included in the family Sphecidae (containing the better-known “cicada killer”), members of this group are now placed in their own family (Crabronidae). Adult females provision their nest with flies, which they catch and sting to paralyze before dragging it down into the burrow. As is common with the social hymenoptera such as bees and paper wasps, these solitary wasps engage in active parental care by providing greater number of prey as the larva grows. As many as twenty flies might be needed for a single larva. I found the burrows of these wasps at first difficult to distinguish from those created by adults of the tiger beetles I so desired, but eventually learned to distinguish them by their rounder shape and coarser, “pile” rather than “fanned” diggings (see this post for more on this subject).

Stichopogon trifasciatusRobber flies (family Asilidae) are a favorite group of mine (or, at least, as favorite as a non-coleopteran group can be). This small species, Stichopogon trifasciatus (ID confirmed by Herschel Raney), was also common on the barren sandy surface. The specific epithet refers to the three bands of alternating light and dark bands on the abdomen. Many species in this family are broadly distributed but have fairly restrictive ecological requirements, resulting in rather localized occurrences within their distribution. Stichopogon trifasciatus occurs throughout North America and south into the Neotropics wherever barren, sandy or gravely areas near water can be found. Adults are deadly predators, swooping down on spiders, flies and other small insects and “stabbing” them with their stout beak.

Chelinidea vittigerPrickly pear cactus (Opuntia humifusa) grows abundantly in the sandy soil amongst the clumps of bluestem, and on the pads were these nymphs of Chelinidea vittiger (cactus bug, family Coreidae). This wide-ranging species occurs across the U.S. and southward to northern Mexico wherever prickly pear hosts can be found. This species can either be considered a beneficial or a pest, depending upon perspective. On the one hand, it serves as a minor component in a pest complex that prevents prickly pear from aggressively overtaking rangelands in North America; however, prickly pear is used by ranchers as emergency forage, and fruits and spineless pads are also sometimes harvested for produce. In Missouri, O. humifusa is a non-aggressive component of glades, prairies, and sand and gravel washes, making C. vittiger an interesting member of the states natural diversity.

Ammophila sp., possibly A. proceraThis wasp in the genus Ammophila (perhaps A. procera as suggested by Herschel Raney) was found clinging by its jaws to a bluestem stem in the cool morning, where it presumably spent the night. One of the true sphecid (or “thread-waist”) wasps, A. procera is a widespread and common species in eastern North America. One of the largest members of the genus, its distinctive, bold silver dashes on the thorax distinguish it from most other sympatric congeners. Similar to the habits of most other aculeate wasp groups, this species captures and paralyzes sawfly or lepidopteran caterpillars to serve as food for its developing brood. Females dig burrows and lay eggs on the paralyzed hosts with which the nests have been provisioned. Adults are also found commonly on flowers, presumably to feed on nectar and/or pollen.

Dusty hog-nosed snakeRich is a bit of herpatologist, so when he brought this hog-nosed snake to our attention we all had a good time pestering it to try to get it to turn upside down and play dead. I had never seen a hog-nosed snake before but knew of its habit of rolling over and opening its mouth with its tongue hanging out when disturbed, even flopping right back over when turned rightside up or staying limp when picked up. We succeeded in getting it to emit its foul musky smell, but much to our disappointment it never did play dead, instead using its shovel-shaped snout to dig into the sand. Dusty hog-nosed snake - head closeupWe had assumed this was the common and widespread eastern hog-nosed snake (Heterodon platirhinos); however, in our attempts to turn it over I noticed its black and orange checker patterned belly. I later learned this to be characteristic of the dusky hog-nosed snake (H. nasicus gloydi), only recently discovered in the sand prairies of southeast Missouri and regarded as critically imperiled in the state due to the near complete destruction of such habitats. Disjunct from the main population further west, its continued survival in Missouri depends upon the survival of these small sand prairie remnants in the Southeast Lowlands.