science

Bee Fly Parasitism of Tetracha virginica

/ Ted C. MacRae / 25 Comments

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

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

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

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

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

Anthrax analis larvae attached to abdomen of Tetracha virginica larva

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

Closer view of anteriormost Anthrax analis larva

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

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

REFERENCES:

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

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

Hamilton, C. C. 1925. Studies on the morphology, taxonomy, and ecology of the larvae of Holarctic tiger beetles (family Cicindelidae).  Proceedings of the U.S. National Museum 65 (Art. 17):1–87.

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

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

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

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

Copyright © Ted C. MacRae 2011

BugShot 2011 – Final Thoughts

/ Ted C. MacRae / 9 Comments

As I suspected would be the case,  has proven to be an especially difficult challenge.  As a result, instead of posting the answer tonight I’m going to give folks another day to make their play for points (remember, nobody walks away empty-handed).  In the meantime, I’ve had a chance to ruminate over this past weekend’s BugShot insect photography workshop at Shaw Nature Reserve in Gray Summit, Missouri, and now seems to be an appropriate time to post some final thoughts while they’re still fresh in my mind. Suffice it to say that it was an incredible experience—both technically and socially.  I learned far more than I thought possible (and hope I can remember even a portion of it) and made some great friends in the process.  It’s really not possible for me to summarize here all of the techniques, insights, equipment choices, etc. that were covered, nor do I want to—such a list would be boring to read and not very meaningful without the context to go with it.  What I would like to do is shout out a few people who, beyond the collective, helped make the weekend what it was for me.

Instructors.  The three instructors, all accomplished insect photographers of the highest caliber, typified three very different yet complimentary approaches to the art.  Alex Wild (University of Illinois), ant photographer extraordinaire and author of the insect blog I’ve most tried to emulate, gave me tremendous insight on lighting and practical approaches on how to use it effectively.  My discussions with John Abbott (University of Texas) about equipment will be very helpful for the type of photography that I like to do (I’m not sure I’m ready for the tripod yet, but maybe the other ideas we discussed will be the “slippery slope”).  Finally, I thoroughly enjoyed my time with Thomas Shahan (Norman, Oklahoma), whose great artistic insight helped me see a whole new world of possibilities for tiger beetle portraiture.  I must admit to feeling a little star-struck when I first began talking to him, but his infectious enthusiasm and exuberance quickly put me at ease.

Friends.  I can’t begin to list everybody whose company I enjoyed, but standouts include Jo Holly (Alex’s better half!), as well as fellow bloggers Crystal, Lee, Dave, and DragonflyWoman.  Even though I only met them this weekend, it was if I had known them for years.  My time “fishing” tiger beetle larvae with Crystal and Lee was not only a highlight of the trip (watching them “jump” as the larva came flying up and out of the burrow was a real treat), but also represented a discovery in the truest sense of the word (as will become clear in a future post).  No discussion of friends would be complete without mentioning James Trager, not only for opening up Shaw Nature Reserve to this weekend’s event, but also for the access he’s given me over the past several years and our frequent, humorous email discussions about all things entomological (or botanical, ecological, etc.).

Gratitudes.  I want to thank Alex for inviting me to take part in this event as something more than just an attendee.  I hope my contribution, however small, was beneficial.  My thanks also to Patsy Hodge, who was so helpful and gracious to me in the days leading up to and during the event.  I also appreciate the kind comments that many of the attendees made to me about my blog and my photographs—your encouragement means a lot to me.

Regrets.  In an event like this, packed as it was with seminars and group discussions, it is sad but unavoidable that one cannot spend at least a little time with each and every person in attendance.  To those that I did have a chance to talk to, the pleasure was all mine.  To those that I missed, I will catch you next time!

I think I’ll close with this minimally processed photograph of what I take to be Misumenoides formosipes (whitebanded crab spider) and its honey bee (Apis mellifera) prey.  Although I photographed this spider using flash and looking straight up into an overcast sky, I managed to properly illuminate the subject and avoid blown yellows and an all-black background by using some of the very techniques and principles that I had just learned earlier that day.  I hope to learn more at BugShot 2012!

Misumenoides formosipes (whitebanded crab spider) | Shaw Nature Reserve, Franklin Co., Missouri

ID Challenge #11

/ Ted C. MacRae / 43 Comments

It’s time for another ID Challenge—can you name the organism(s) shown here?  I’ll give two points each for the correct order, family, genus and species.  Additional points will be awarded on a discretionary basis for relevant natural history comments.  Standard challenge rules apply, including moderated comments during the challenge period (you don’t have to be first to score points), early-bird points to those who do arrive at the correct answer before others, etc.  Ben Coulter has a solid lead in BitB Challenge Session #4, but there are enough challenges left in the current session that his lead is not secure—do you have what it takes to put together a run to bump him off the podium top spot?

Shaw Nature Reserve, Franklin Co., Missouri

Copyright © Ted C. MacRae 2011

BugShot 2011 – Lesson 2

/ Ted C. MacRae / 11 Comments

Most of my insect photography is done up close using fast shutter speeds (to prevent motion blur) and small apertures (to maximize depth of field).  This necessitates the use of full flash – the amount of light reaching the camera sensor at f/16 and 1/250 sec is not enough to show any image at all, much less one properly exposed.  Full flash photography has its own set of challenges, but for the most part it can be used to produce excellent closeup photographs of insects, even very small ones.  One thing that has always bothered me about full flash photography, however, is the “black background” effect when photographing an insect sitting up on a plant without something else in the immediate background to reflect light.  Not that I don’t like black backgrounds—they can be used to stunning effect with the right subject.  I just don’t want it to be my only option for insects that I photograph up off the ground. Of course, it is rather a simple matter to place something in the background that is close enough to reflect light but far enough away to remain out of focus, but what I really want to be able to do sometimes is have a blue sky.  I always thought this meant natural light, with its low f stops, slow shutter speeds, and the resulting motion blur and loss of depth of field. 

Of the many things I learned today, how to include a blue sky background in a closeup photograph at f/16 was my favorite.  This is accomplished by bumping up the ISO to 400 (to make the camera sensor more receptive to light) and decreasing the shutter speed to 1/60 sec.  Keeping the f stop high maintains the depth of field, but the increased ISO and decreased shutter speed allows sufficient light from a sky background to register on the sensor.  By themselves, however, these setting will still result in an underexposed subject, which is illuminated instead by fill flash.  Despite the slower shutter speed, there is no motion blur because the “effective” shutter speed for the subject is the duration of the flash pulse rather than the camera shutter speed—it’s like combining two exposure speeds in a single photograph, one for the background and another for the subject.

The following three photographs illustrate this principle—again, they are not technically perfect photos, but rather the result of quick experimentation to understand the principles involved.  Photo 1 is from yesterday’s post and illustrates what my typical settings have always been: ISO 160, f/16, and 1/250 sec.  It’s a decent photo of the treehopper, Acutalis tartarea; however, black is perhaps the least appropriate background to choose for this black species. Until now, it would have been my only option unless I tried arranging foliage in its background.  Photos 2 and 3 are of another individual of this species that I found today (fortunately in similar orientation to the individual photographed yesterday).  In both photos I kept the flash unit set to ETTL (adjusting FEC as appropriate for the shots).  In Photo 2 I bumped up the ISO to 400 but kept the shutter speed fast (1/200 sec)—you can see some effect in that the background is not truly black, having received some light from the blue sky.  It’s not enough, however, because the shutter speed was still too fast.  In Photo 3 the ISO remained at 400 but the shutter speed was also decreased to 1/60 sec.  The shutter staying open that long allows enough light from the sky to register on the sensor and, Voila!, we have a blue sky background that creates nice value contrast with the black subject.  The subject these photos is not terribly sharp, but that is just lack of focus—not motion blur from a slow shutter (sorry, I was just practicing settings rather than going for a perfect shot). All three photos were shot with the Canon 100mm macro lens + 68 mm of extension tube (total magnification ~2X).

''Typical'' insect macro settings: ISO 160, 1/250 sec, f/16

ISO increased to 400 (1/200 sec, f/16)

Shutter speed decreased to 1/60 (ISO 400, f/16)


Copyright © Ted C. MacRae 2011

BugShot 2011 – Lesson 1

/ Ted C. MacRae / 7 Comments

I’m a lucky guy! First, I’m one of the fortunate attending this weekend’s BugShot insect photography workshop. Second, this first-of-a-kind event is being held only 13 miles from my home at Shaw Nature Reserve in Gray Summit, Missouri. Third, I was “adopted” by the BugShot instructors to assist in the event. Who are the instructors? None other than John Abbott from Austin, Texas—an expert on dragonfly biology and insect action photography, Thomas Shahan from Norman, Oklahoma—master of close-up arthropod (especially jumping spider) portraiture, and Alex Wild from Champaign-Urbana, Illinois—ant photographer extraordinaire and author of the most popular insect blog on the net.  In 2009 I picked up a digital SLR camera for the first time ever—in 2011 I am rubbing shoulders, discussing exposure and lighting, and enjoying social time with three of the country’s most accomplished insect macrophotographers (and some other very cool people as well).

I have come a long way, but I still have much to learn.  Intimate understanding of lighting, exposure, and the creative use of flash still eludes me—I can do a few things well, but there is much more I can’t do at all.  Today was my first time experimenting with the effect of lighting direction, i.e. taking the flash heads off their fixed position on the front of the lens and hand-holding them in different positions.  This simple technique can have dramatic effects on the look of a photograph, as illustrated by the following two photographs.  In the first, both flash heads of my Canon MT-24EX twin flash are attached to the front of the lens (as they have been for every single flash photograph I’ve ever taken up to this point).  In the second, only the right flash head remains attached to the lens, while the left head has been detached and is being hand-held directly above the subject (in this case, the treehopper Acutalis tartarea on Solidago sp.).  Technically they are not very good photographs, but they illustrate well the dramatic differences that can be achieved by varying the position of the flash heads.  Among other things, this is a technique that I will be exploring much over the coming weeks.

Both flash heads attached to front of lens.

Right flash head attached to front of lens; left flash head held directly above subject.

Copyright © Ted C. MacRae 2011

Bumelia borer on white

/ Ted C. MacRae / 19 Comments
Plinthocoelium suaveolens suaveolens | Ozark Co., Missouri

Last weekend I visited one of my favorite collecting spots in all of Missouri—Long Bald Glade Natural Area (part of Caney Mountain Conservation Area in Ozark Co.).  Nestled at the eastern edge of the White River Hills in southwestern Missouri, its deeply dissected hills are home to numerous plants and animals that are more typical of the southern Great Plains and which have found refuge in the xeric, thin-soiled calcareous prairies (commonly “cedar glades”) that cover the area’s southern- and western-facing slopes.  These include some rather impressive insects, such as a disjunct population of Cicindelidia obsoleta vulturina, which I just found here last year as the new northeasternmost extent of the population, as well as the marvelously monstrous Microstylum morosum, North America’s largest robber fly and so far known in Missouri only from Long Bald Glade where it was discovered in 2009. 

Another quite striking insect found at Long Bald Glades (though not restricted in Missouri to the White River Hills) is the bumelia borer, Plinthocoelium suaveolens.  This beetle occupied much of my time in July 2009 as I committed to photographing the species in the wild, and it was Long Bald Glade where I finally (if not completely satisfactorily) succeeded in that goal.  This time I was visiting the Glade to look for the earliest individuals of C. obsoleta vulturina and, hopefully, document additional glades within Caney Mountain that might support the beetle.  However, in the back of my mind I was also keeping a lookout for P. suaveolens—this species is primarily active during July and August in Missouri, but I do have records of it as late as September.  As I looked for (and found) tiger beetles, I also checked out each bumelia tree that I passed hoping to see a P. suaveolens adult perched on its lower trunk.  It was not until later in the afternoon that I heard a loud “buzz” approaching from behind and turned to see one of these beauties fly right past me—legs and antennae held outstretched—before landing on a nearby tree.  Now, over the years I’ve learned a few lessons, and one is that you don’t try to take in situ photographs of the first individual you encounter of a prized species.  More often than not it gets away before you even fire the first shot, and you’re left with nothing.  My standard procedure now is to procure the first individual immediately and keep it alive.  If attempts to photograph subsequent individuals are not successful (or none are seen), then at least I have a backup for studio shots (not my first choice, but better than nothing!).  Such was the case with this individual.

Although I still lack that “perfect” beetle-on-a-branch shot that I hope to eventually get for this species, it seemed a good subject for some white-box photography.  I’ve vacilated between true white-box w/ indirect flash versus getting a white-box effect by using direct, diffused flash with the subject on a white background.  I decided now was the time for a direct comparison of the two techniques.  All of the following photographs were taken with the Canon 100mm macro lens on a Canon 50D body at 160 ISO, 1/200 sec, and f/16.  For the closeups (photos 3 and 5 of each series), 68mm of extension tubes were added.  The photos on the left are true white-box photos, i.e. the flash heads were directed up and away from the subject placed inside a box lined with white tissue (Kim-Wipes laboratory wipers).  The photos on the right mimic the white-box effect by placing the subject on white filter paper, but the flash heads were pointed directly at the subject through my DIY concave diffuser (click on photos for 1200×800 versions):

Indirect flash in white box

Direct flash w/ DIY diffuser

Indirect flash in white box

Direct flash w/ DIY diffuser

Indirect flash in white box

Direct flash w/ DIY diffuser

Indirect flash in white box

Direct flash w/ DIY diffuser

Indirect flash in white box

Direct flash w/ DIY diffuser

I must admit, looking at the photos on the camera playback screen I had the impression that I would like the direct-diffuser photos better, but after reviewing them on the computer and applying typical post-processing enhancements (e.g., levels, slight shadow reduction, and unsharp mask), the true white-box photos appear to have benefited from more even lighting, resulting in truer color, less shadowing, and minimal specular highlighting.  Not that the direct-diffuser photos are bad—they’re just not as good as the white-box photos.  I guess what this means is that my DIY diffuser, while a significant improvement over my previous diffusers, still could use some improvement (if ability to create white-box-like results is the ultimate test of a diffuser’s effectiveness).  I’d be interested in knowing your opinions based on these comparisons.

Congratulations to Ben Coulter, who wins yet another Super Crop Challenge and strengthens his lead in the overall standings of the current BitB Challenge Session #4 with 13 points.  Mr. Phidippus also correctly identified the species and takes 2nd place in the challenge with 8 points, keeping him in 2nd place in the overall standings as well.  Morgan Jackson takes 3rd place in the challenge with 7 points, but Roy’s retains 3rd place in the overall standings by way of his 6 points in this challenge.  Congratulations to these top points earners, and thanks to all who played.

Copyright © Ted C. MacRae 2011

Super Crop Challenge #9

/ Ted C. MacRae / 14 Comments

Can you name the structures in this photo (easy) and the critter they belong to (maybe not so easy)?  Because there are so many potential answers to those two questions, I’ll give 1 point for each correctly named structure (5 maximum) and taxon (primary categories from class to species).  As always, standard challenge rules apply, including moderated comments to allow time for everyone to submit their answers.  Bonus points will be awarded to early birds if multiple participants arrive at the same correct answer and possibly also for other relevant comments at my discretion.

The competition is really heating up in the current Session #4—current leader and 2-time champ Ben Coulter has 22 points, but there are at least half a dozen folks who could easily earn enough points in this one challenge to either take the lead or grab a podium spot.  If you’re stumped, remember that the pity points you earn now could be a tie-breaker at the end of the session.  Good luck!

Copyright © Ted C. MacRae 2011

Peek-A-Boo!

/ Ted C. MacRae / 4 Comments

Dissosteira carolina (Carolina grasshopper) | Jersey Co., Illinois

Despite the geographic specificity of its scientific and common names, the Carolina grasshopper (Dissosteira carolina) can be found in every state of the contiguous United States and adjacent provinces of Canada. Its large size, cryptic coloration with yellow hind wings, tendency of males to crepitate during flight (a snapping or crackling sound made by rubbing the under surface of the forewings against the veins of the hind wings), and distinctively chunky nymphs would normally be enough to attract a lot of attention were it not also among the most overwhelmingly ubiquitous of grasshoppers throughout much of its range. I could give all sorts of information about its food habits, migration and dispersal behavior, daily activities, etc., but this would be redundant given the excellent Species Fact Sheet that has been generated for it by the Wyoming Agricultural Experiment Station (Pfidt 1996).

This individual was found in a soybean field in Jersey Co., Illinois. They are extremely wary and perhaps the most difficult-to-approach grasshopper I’ve encountered yet. Considering my particular fascination with oedipodine grasshoppers, I felt compelled to take some photographs—but, my God, there are already a godzillion photos of this species on the web.  I decided to limit myself to this one rather unusual perspective and leave it at that!

REFERENCE:

Pfidt, R. E.  1996. Carolina Grasshopper Dissosteira carolina (Linnaeus). Wyoming Agricultural Experiment Station Bulletin 912, Species Fact Sheet, 4 pp.

Copyright © Ted C. MacRae 2011