The Methocha

/ Ted C. MacRae / 5 Comments

As pointed out in my recent post, , there is much to learn still regarding tiger beetle larval parasitoids. In addition to bee flies (order Diptera, family Bombyliidae) of the genus Anthrax, tiphiid wasps (order Hymenoptera, family Tiphiidae) in the genus Methocha also parasitize tiger beetles in their larval burrows. Unlike bee flies, however, which sneakily lay their eggs in and around tiger beetle burrows when their victim isn’t watching, Methocha females aggressively engage the larva and even allow themselves to be grasped within the beetle larva’s sickle-shaped mandibles in order to gain entry to the beetle’s burrow.

Methocha appears to be a rather diverse genus, but it’s taxonomy is still incompletely known. George Waldren from Dallas, Texas is working on a revision of the genus and has found several new species in Texas alone. George is interested in seeing Methocha material from other areas as well and recently sent me the following reminder that adult females are active now:

…if you know of any areas with many tiger beetle larvae, now is the time to find Methocha. They superficially look like Pseudomyrmex ants, but once you see one you’ll catch on to them quickly. I collected more than 70 females today in a large aggregation of Tetracha carolina burrows.

In a subsequent message he adds:

Collect as many as you can, since they seem to be highly seasonal and rare most of the year. I almost always find them around beetle populations in sandy creek beds and receding bodies of water. A pooter works best if they are abundant and there isn’t much for them to hide under. Using your fingers also works—the sting is mild and usually doesn’t pierce the skin (depends on the person and size of the wasp). Vial collecting one by one works just as well.

Methocha females are generally overlooked due to their specialized life history and few specimens are in collections. Males are better represented since they’re easily collected with malaise traps.

If you have any Methocha specimens or manage to collect some, please contact George (contact info can be found at his BugGuide page). BugGuide does have a few photographs of these wasps to give you an idea of what they look like, but this excellent video titled “The Methocha” from Life in the Undergrowth with David Attenborough provides an unparalleled look at their appearance and behavior:


Copyright © Ted C. MacRae 2011

Different Jaws for Different Jobs

/ Ted C. MacRae / 19 Comments

Arrhenodes minutus (oak timberworm) | Wayne Co., Missouri

If you’re interested in wood boring beetles and live in the eastern  U.S. like I do, you’re sure to encounter sooner or later the region’s sole¹ “primitive weevil” (family Brentidae), the oak timberworm (Arrhenodes minutus).  This beetle develops as a larva in the wood of living trees exposed by wounding, creating numerous small “worm holes” that can occasionally degrade the value of wood grown for timber.  Females are presumably attracted to volatiles given off by wounded wood for oviposition, thus they are also commonly attracted to the trunks and stumps of trees harvested for lumber or cut for some other reason.  Cut trees are also highly attractive to wood boring beetles in the families Buprestidae and Cerambycidae—my primary taxa of interest, so I’ve seen more than a few oak timberworms over the years, including this male and female that I found on the cut stump of a large black oak (Quercus velutina) in Sam A. Baker State Park, Wayne Co., Missouri.

¹ Actually, there are three other species in eastern North America as well, but all are Neotropical species that occur no further north than the southern tip of Florida (Thomas 1996).

Female - beak thin and elongate

Male - beak short w/ robust mandibles

An interesting feature of oak timberworms and related species of primitive weevils is the rather extreme sexual dimorphism exhibited in the shape and function of the mandibles.  Mandibular sexual dimorphism is actually quite common across many groups of beetles, but in most cases the males simply have proportionately larger mandibles than females due to their use in sexual combat (think stag beetles, for example).  Oak timberworm males also have enlarged mandibles for combat with other males (males are territorial and guard females during oviposition).  The females, however, rather than simply having smaller yet similarly shaped versions of the male mandibles, instead have tiny little mandibles at the end of a greatly narrowed and elongated rostrum (beak).  This is because, unlike most other beetles in which the female mandibles lack a specific purpose, female oak timberworms use their mandibles to “drill” holes into the wood in which they will insert their eggs.  Different forms for different functions!

Mate-guarding behavior

I have read reports of males assisting females in removing her beak if stuck in the wood while drilling an egg hole by “stationing himself at a right angle with her body and pressing his heavy prosternum against the tip of her abdomen, her stout fore legs thus serving as a fulcrum and her long body as a lever” (Riley 1874, as quoted in Thomas 1996), making this a rare instance of tool use by insects.  I have not observed this behavior myself, but it is common to find the males in various mate guarding positions over the female as pictured above.

REFERENCE:

Riley, C. V. 1874. The northern brenthian—Eupsalis minutus (Drury). (Ord. Coleoptera; Fam. Brenthidae). Sixth Annual Report on the Noxious, Beneficial, and Other Insects, of the State of Missouri. Began and Carter, Jefferson City, Missouri, 169 pp.

Thomas, M. C. 1996. The primitive weevils of Florida (Coleoptera: Brentidae: Brentinae). Florida Department of Agriculture & Consumer Services, Division of Plant Industry, Entomology Circular No. 375, 3 pp.

Copyright © Ted C. MacRae 2011

Ozark Landscapes – White River in northern Arkansas

/ Ted C. MacRae / 13 Comments

White River near Calico Rock, Arkansas

One of my favorite insect collecting sites is a system of sandstone glades in the White River Hills of north-central Arkansas. Overlooking the White River as it courses past the quaint little town of Calico Rock, the glades atop these towering bluffs host a rich diversity of insects—some attracted from the surrounding woodlands, others restricted only to the glades. I had not visited the area before this year but went there five times this season—twice in June, once in July, once in August, and once in September.  Of the many insect species I found here this season, some of the more interesting include:

Copyright © Ted C. MacRae 2011

Crossidius coralinus fulgidus

/ Ted C. MacRae / 22 Comments

Crossidius coralinus fulgidus | Uintah Co., Utah

Tiger beetles may have been the primary focus of last week’s 9-day, 10-state, 4,700-mile collecting trip; however, they were not the only beetles I was hoping to see. Longhorned beetles (family Cerambycidae) of the genus Crossidius are unusual in the family because of their fall rather than spring/summer adult activity period, and they just happen to occur in dizzying variety throughout the Great Basin and surrounding mountainous areas. Larvae of all species are presumed to feed on the roots of perennial, shrubby, fall-blooming composites, primarily in the genera Chrysothamnus, Ericameria, Gutierezzia, and Haplopappus (Linsley and Chemsak 1961), with the adult activity period undoubtedly timed to allow congregation and mating on the late-season blooms of their host plants.  Only 13 species are currently recognized, but these are further divided into 37 subspecies and innumerable locally distinct populations.  Not having spent much time in the mountain west during the fall, this group has till now been poorly represented in my collection.

The species shown here, Crossidius coralinus fulgidus, was among the first of many that we encountered during our trip.¹  This population was seen near Vernal in northeastern Utah.  It was late in the day and the adults had settled for the night onto the flowers of their host plant, Ericamera nauseosa.  Flower-visiting longhorned beetles are notoriously frustrating subjects to photograph, as their constant movement and long legs and antennae make focus and composition difficult.  These beetles had essentially ceased activity, allowing me to carefully compose and focus the shot, and the low sun in the western sky provided a bright blue eastern sky to use as a colorfully contrasting background.  The photo above (the very long antennae identify it as a male) was taken hand-held with my Canon 100mm macro lens at ISO 400 and 1/60 sec to allow exposure of the sky and flash at an aperture of f/16 to illuminate the subject and achieve good depth of field.  My only criticism of this photo is the small amount of blur seen in the distal antennal segments.

¹ “We” refers to myself and Jeff Huether from Geneva, NY. Jeff is primarily interested in Meloidae but like me also has an interest in Cerambycidae. I was fortunate to have Jeff with me on this trip, as he has collected extensively throughout the Great Basin region and encountered nearly all of North America’s named species and subspecies of Crossidius. It is only because of his prior experience with this group that I was able to find this and several others that we saw during the trip.

ISO 100, 1/200 sec

ISO 400, 1/200 sec

ISO 400, 1/60 sec

Because the beetles were so calm, I spent some time with this female individual trying different settings to see their effect on background color, subject illumination, and detail.  All were taken hand-held using the same lens at f/16, with the left photo also using my “typical” settings of ISO 100 and 1/200 sec.  The background is very dark (in post-processing I might choose to make it black)—good for some subjects but not this one, and although the focus is good the lighting is rather harsh (I had to decrease highlights in post-processing much more than I normally like).  The center photo was taken with ISO increased to 400 and results in a much more pleasing, if still not very natural-looking sky background.  Focus remains good and the shorter flash duration needed reduces the amount of highlighting that needs post-processing adjustment.  Overall I like this photo the best except that the sky is not true in color.  The right photo is also at ISO 400 but uses a slower shutter speed (1/60 sec).  The sky in this photo is the most natural-looking, and as might be expected problems with flash highlights are minimal—it almost looks like a natural light photograph.  However, some amount of motion blur can be detected, especially in the antennae.  Perhaps intermediate shutter speeds (e.g. 1/120 sec) or slightly higher ISO might effectively deal with this while still allowing the truest colors.  What do you think?

REFERENCE:

Linsley, E. G. and J. A. Chemsak.  1961.  A distributional and taxonomic study of the genus Crossidius (Coleoptera, Cerambycidae).  Miscellaneous Publications of the Entomological Society of America 3(2):26–64, 3 color plates.

Copyright © Ted C. MacRae 2011

Cicindela scutellaris yampae – Yampa Festive Tiger Beetle

/ Ted C. MacRae / 6 Comments

In A Field Guide to the Tiger Beetles of the United States and Canada (Pearson et al. 2006), Cicindela scutellaris yampae (Yampa Festive Tiger Beetle) is one of 223 species and subspecies listed in the book’s index to species and subspecies. Although the book’s alphabetical listing places it second to last in the list, it surely must be considered near the top of any list based on beauty. It is also among the most geographically restricted tiger beetles in North America, restricted to the Maybell Sand Dunes in northwestern Colorado where it occurs with the equally beautiful, rare, and restricted Cicindela formosa gibsoni (Gibson’s Big Sand Tiger Beetle). Like that subspecies, C. s. yampae was one of six endemic sand dune tiger beetles targeted in this year’s Annual Fall Tiger Beetle Trip™, and as these photos show I was lucky enough to find it.

Cicindela scutellaris yampae | nr. Maybell, Colorado

As a species, C. scutellaris is one of North America’s most widely distributed and polytopic species, with the nominate and lecontei forms inhabiting a wide swath of the Great Plains and Midwest.  Around the eastern, southern, and western perimeters of its geographical distribution occur numerous named subspecies exhibiting a tremendous diversity of variations on the species’ “normal” coloration and maculation.  Cicindela s. yampae is most similar to the nominate subspecies due to its green head and prothorax with purple-red elytra, but it differs in possessing a broad white maculation on the side of each elytron (top photo).  There are individuals, however, in which the maculation is reduced to isolated spots (bottom photo), resembling somewhat the pattern of maculations seen in C. s. lecontei further to the east.

C. scutellaris yampae w/ reduced maculations

Pearson et al. (2006) note that records over the years suggest the remaining populations of this beetle are small. We did not see many individuals on our visit to the type locality east of Maybell early this past week (perhaps no more than seven total), and we saw none at a formerly larger sand dune about 10 miles west of Maybell.  In past years this latter site has supported good numbers of the beetle, but it has apparently succumbed to vegetational encroachment of the formerly more open sand dune. As far as I am aware there are no conservation measures in place on any level to protect these remaining populations and ensure that adequate suitable habitat remains to enhance the beetle’s long-term prospects.

REFERENCE:

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

Copyright © Ted C. MacRae 2011

Cicindela formosa gibsoni… or not!

/ Ted C. MacRae / 11 Comments

Last Friday I began the 2011 Annual Fall Tiger Beetle Trip™. This year’s edition was actually a last-minute change—my original plans to collect wood for rearing wood-boring beetles in south Texas thwarted by that state’s long and continuing drought (along with the unwillingness of some of the area’s federal wildlife refuge managers to grant my research study permits despite the work I’ve done there in past years—apparently only institutional and not personal research is now deemed credible by these courageous individuals who are doing their best to protect the natural resources in their charge). My travel funds are limited, and rather than throw good money at a bad situation, I decided to pursue greater chances of success and make the trip that I have wanted to do for some time now—the Great Sand Dunes tour through the Rocky Mountains and Great Basin. The target species include many of the classic western sand dune species, and I hope to feature most of them in the days and weeks after the conclusion of the trip this coming weekend.

Cicindela formosa gibsoni | nr. Maybell, Colorado

The first of these target species that I encountered is the subject of this post, Cicindela formosa gibsoni (Gibson’s Big Sand Tiger Beetle).  This large, robust, and gorgeously marked subspecies is highly restricted in occurrence, curiously to two areas separated by more than 1,000 km—the Maybell Sand Dunes in northwestern Colorado (Moffat County) and the Great Sand Dunes of southwestern Saskatchewan.  It is distinguished from the nominate form and other subspecies by having the white markings of the elytra so expanded in most individuals that they coalesce and cover nearly the entire elytral surface.  The result of such a large white surface with contrasting red-purple head, thorax, and elytral sutural area is one of North America’s most spectacularly marked tiger beetle species.  The individual photographed here was one of many observed a few days ago on the Maybell Sand Dunes¹, and I feel truly lucky to have been able to personally witness these striking beetles flying powerfully across the dunes in their small home range, landing far away with the comical bounce and tumble that is characteristic of this and the other subspecies.

¹ In the interest of full disclosure, these photos were taken later in the day using subjects confined in a terrarium of native substrate. I had intended to photograph them in the field; however, they unexpectedly began digging burrows around 2 p.m., and my efforts to stalk the last few stragglers before they disappeared were not successful.


An interesting situation occurs regarding the taxonomy of this subspecies.  Despite the nearly identical appearance of adults from both the Saskatchewan and Colorado populations, logic and differences in larval coloration suggest that these two populations have arisen independently, their common appearance a result of convergence rather than shared ancestry.  Molecular studies are in progress to determine more conclusively whether this is true (hopefully augmented with material collected during this trip).  The subspecies was originally described based on specimens collected in Saskatchewan, thus, if convergence is confirmed the Maybell population will find itself needing a new name.

Congratulations to Doug Taron, who narrowly beat perennial heavyweight Ben Coulter, Tracy Mormon and Mr. Phidippus for the ID Challenge #12 win.  The overall standings remain unchanged, with Ben still in the lead with 65 points, Mr. Phidippus 2nd with 54 points, and Roy completing the podium at 39 points.  The final standings may seem like a lock, but there will still be one more challenge in the session—anything can happen!

Copyright © Ted C. MacRae 2011

ID Challenge #12

/ Ted C. MacRae / 29 Comments

This should be a relatively easy ID Challenge compared to previous editions—2 points each for the correct order, family, genus, species, and subspecies.  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 maintains a commanding lead in BitB Challenge Session #4, but with this and one more challenges left in the current session is his lead secure?

Copyright © Ted C. MacRae 2011

My Canon 8X Macro Lens

/ Ted C. MacRae / 37 Comments

For the past few months I have started routinely using extension tubes with my 100mm macro lens for photographing tiger beetles. I do this primarily because for most tiger beetles and other insects in the smallish to medium-sized range I need the capability to go both above and below 1X magnification, meaning that I must constantly switch between my Canon 100mm lens (1X maximum) and MP-E 65mm lens (1X minimum). With a full extension tube set (68mm), my 100mm macro lens effectively becomes a 0.7–2.0X macro lens, a nice range of magnifications for most of the photographs that I take. There is a secondary benefit to this in that the subject-to-lens distance is decreased somewhat, allowing me to get the MT-24EX flash heads closer to the subject for better lighting.

Lately I’ve been wondering what the magnification capabilities would be if I added extension tubes to the 65mm lens.  With a maximum magnification of 5X, it hardly seems that even more magnification would ever be needed, but who knows what uses one might find if the capability exists.  In theory, it seemed like it should work—after all extension tubes are simply tubes with no glass (in fact, the 65mm lens itself is simply a macro lens with a very expensive, built-in bellows).  The only consideration was whether the focal plane would remain outside of the lens.  Tonight I finally decided to sit down and try it out, and the results were really quite stunning.  The three photos below show an ordinary pencil lead, the first with the 65mm lens alone set at 1X, the second with the lens set at 1X plus full extension tubes, and the third with full extension tubes and the lens set at 5X.  The full extension tube set provides an additional ~1.7X magnification, making the 65mm lens effectively a 1.7–8.0X macro lens!

Canon MP-E 65mm lens @ 1X

Canon MP-E 65mm lens @ 1X + 68mm extension tubes (= 1.7X)

Canon MP-E 1-5X macro lens @ 5X + 68mm extension tubes (= 8X)

The subject-to-lens distance is indeed quite short—only about 38mm or so.  However, having at my disposal an 8X macro lens suddenly opens up a whole new world of ideas for insect macrophotography.  Knowing that the combination of 65mm lens and extension tubes is possible, I just had to try this out on a living subject—like now!  I happened to have in a terrarium a subject from the day’s collecting, so I tried it out—again with the 65mm lens fully extended to result in 8X magnification.  Shown below is a example of this lens combination at full magnification, completely uncropped—can you name the subject?

Canon MP-E 65mm lens @ 5X + 68mm extension tubes (= 8X)

Copyright © Ted C. MacRae 2011