Third time’s a charm!

This post may seem like déjà vu to some of you, as it is my third featuring our common woodland tiger beetle species, Cicindela sexguttata (six-spotted tiger beetle). However, this post is as much a photography lesson as it is insect post, and when I say photography lesson I mean for myself – I’m not yet anywhere near the point where I feel qualified to dole out photography advice to others.

The last weekend of May, I returned to nearby Shaw Nature Reserve in hopes of photographing Cicindela unipunctata (one-spotted tiger beetle). This large, nearly flightless species has been recorded broadly across the eastern U.S. but is not encountered all that commonly. It is among the few species that seem to prefer more shaded woodland habitats (Pearson et al. 2006); however, its ecology is still not well understood. I had hoped to find it during my first outing with the new camera setup, but it was not to be and I had to settle for C. sexguttata as the first tiger beetle subject for my camera’s maiden voyage.   On this return visit, I arrived at the preserve shortly before noon and proceeded to walk back and forth along the trails where my colleague, Chris Brown, had noted healthy populations last year and one individual just three weeks ago.  For four hours, I gazed intently at the path in front of me in hopes of seeing the beetle – usually blending well with the ground because of its dull brown upper surface and noticed only because of its clumsy manner of running when disturbed.  All to no avail.  Of course, our old friend C. sexguttata was still present in good numbers, and since I wasn’t completely happy with the results of my first photo shoot of this species with the new camera I decided to try it again.

My main criticism of the initial photographs of this species was the harshness of the lighting.  I suspected that diffusers of some type would give a better result, so for this outing I covered the flash heads with small plastic diffuser caps that I had purchased with the flash unit.  The following series of photographs compare the results with and without the diffuser caps.  The photos have been left unenhanced but are reduced from their original size to 1200×800 pixels.  All of the photographs were taken using a Canon EF 100mm macro lens on a Canon EOS 50D, ISO 100, exposure 1/250 sec, and MT-24EX twin flash unit.  Click on the photos to see the enlarged version after reading the discussion of each.

Flash 1/4 power without diffuser caps, f/20

Flash 1/4 power without diffuser caps, f/20

This first photo is from the first session, during which I ran the flash unit at 1/4 power without diffuser caps.  The conditions were rather bright, and it required a relatively high f-stop (f/20) to get the exposure right.  This resulted in very good depth of field, but as you can see the lighting is rather harsh with bright highlights due to the brilliant, metallic coloration of the beetle.

1/8 power flash w/ diffuser caps

Flash 1/8 power flash with diffuser caps, f/10

In this photograph, I reduced the flash power to 1/8 and used the diffuser caps.  This softened the light considerably and removed much of the harsh highlighting.  However, I had to open up the aperature to f/10 in order to get good exposure, and as a result the depth of field really suffered.  Apparently the diffuser caps also reduce the amount of light from the flash, which combined with reducing the power to 1/8 substantially lowered the light levels.

Flash 1/4 power, w/ diffuser caps, f/13

Flash 1/4 power with diffuser caps, f/13

I then increased the flash back up to 1/4 power but kept the diffuser caps in place.  This allowed me to increase the f-stop to f/13, which resulted in much better depth of field.  Since this photograph was taken in fairly bright conditions, this suggests that I might want to go up to 1/2 power flash in lower light situations if I want to maintain a higher f-stop.  I am very happy with this photograph – the lighting is even with no harshness, and virtually the entire beetle from foreground to background is in focus.  A little post-processing might still be helpful for reducing the shadows a bit, but otherwise I think this is a pretty good standard to shoot for with my future tiger beetle photographs.

Photo details: Canon EF 100mm macro lens on a Canon EOS 50D, ISO 100, 1/250 sec, f/13, MT-24EX flash 1/8 power with diffuser caps

Cicindela unipunctata - flash 1/8 power with diffuser caps, f/13

As the saying goes, patience rewards those who wait, and a short time before I needed to leave, I finally saw the first C. unipunctata.  I was lucky enough to see it on the path without first disturbing it and was able to slowly crouch down into position and roll off a series of photos from this angle.  The photo I share here seemed to be the best of the series, but as I tried to shift to get a different view the little bugger began to bolt.  I blocked his escape with my hands until he seemed to settle down and then looked for him in the viewfinder, but I couldn’t find him – he had bolted as soon as I took my eye off of him, never to be seen again.  It amazes me how a relatively large beetle such as this – flightless even – can disappear completely amongst the vegetation.  Nevertheless, I accomplished my goal of getting at least one good photograph of this species, and you can be sure that I’ll be back to try for more.

I know there are several quite capable insect macrophotographers out there that occasionally read this blog – I encourage any comments or feedback that you might have on the techniques I have discussed here.

Copyright © Ted C. MacRae 2009

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.

Add to FacebookAdd to NewsvineAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to Ma.gnoliaAdd to TechnoratiAdd to Furl

Brachys on oak

Although the beetles I photographed for my springtime Acmaeodera post are among the smaller buprestids occurring in Missouri, they are by no means the smallest. That honor belongs to the curious little genus Mastogenius, measuring only around 2 mm in length and, thus, looking for all intents and purposes like little black dots.  Slightly larger, but still smaller than our smallest Acmaeodera, are members of the tribe Trachyini.  Adults in this group exhibit a highly derived morphology compared to other groups of jewel beetles – flat, compact, and wedge-shaped rather than the elongate, cylindrical form more commonly associated with the family.  This seems in part due to their unique larval habits – mining within the leaves of their host plants rather than boring through the wood.  Three genera in this tribe occur in the U.S.¹, all of which are found in Missouri.  These include: 1) Taphrocerus, which mine the leaves of sedges (family Cyperaceae); 2) Pachyschelus, which mine the leaves of herbaceous plants in several families – primarily Fabaceae; and 3) Brachys, which mine the leaves of hardwoods, chiefly oaks (Quercus).  It was two species in this latter genus (out of three that occur in Missouri) that I encountered a couple weekends ago at Reifsnider State Forest in Warren County (noted for its high quality example of a mature white oak forest).

¹ A species in the Old World genus Trachys was introduced to North America from Europe and is established in New Jersey.

Brachys_ovatus_IMG_0193_enh2

Photo details: Canon MP-E 65mm 1-5X macro lens on a Canon EOS 50D, ISO 100, 1/200 sec, f/10, MT-24EX flash 1/8 power through diffuser caps

Brachys ovatus is the largest of the three species, usually measuring a little more than 5 mm in length. In addition to size, it can also be distinguished from Missouri’s two other species of Brachys by the dense row of long hairs occurring along the apex of the last abdominal sternum. For those of you who prefer not to have to look at the underside of its butt, the white-margined band of bronze pubescence before the apex of the elytra and longitudinal rows of bronze setae in the basal half of the elytra are usually sufficient for distinguishing this species.  Brachys ovatus is a common associate of oaks throughout Missouri during spring – I have collected it on ten of Missouri’s 21 oak species, including both ‘white oaks’ and ‘red oaks’. Despite its common occurrence on oak and the frequent reference to it in the literature as a leaf-miner of oaks, few reliable rearing records exist to document the range of hosts it actually utilizes.  There are older reports of this species mining the leaves of other hardwoods such as beech (Fagus), elm (Ulmus), hickory (Carya), and hornbeam (Carpinus); however, the veracity of these reports is questionable, and they may refer only to incidental adult associations.

Brachys_aerosus_IMG_0165_enh2

Photo details: Canon EF 100mm f/2.4 Macro Lens with Kenco extensions on a Canon EOS 50D, ISO 100, 1/200 sec, f/11, MT-24EX flash 1/8 power through diffuser caps

Brachys aerosus is another commonly encountered species.  This is a highly variable and hard-to-define species, but in general it can be recognized by the basal region of the elytra largely lacking pubesence and with a purple, blue, or green luster, and by the predominantly gold to bronze pubescence covering the apical area of the elytra.  Adult length is generally from 3 to 5 mm – somewhat smaller than B. ovatus, and differing also in that it is commonly associated with a variety of hardwoods besides oak.  In Missouri, I have primarily collected it on oaks and elms.  Literature reports – mostly old and unreliable – record as larval hosts many other hardwood genera such as chesnut (Castanea), beech, hazel (Corylus), hickory, hornbeam, linden (Tilia), poplar (Populus), and even such unlikely genera as huckleberry (Vaccinium) and grape (Vitis).  Because of its variability and the broad diversity of hosts with which it has been associated, this species is suspected of acutally being a species complex.  The late George Vogt spent many years making careful observations with reared material in an effort to determine species boundaries and their host associations. Unfortunately, Vogt passed away before publishing his observations, and his eccentric record keeping with cryptic notes (Anderson et al. 1991) makes it unlikely that they ever will be published. It will take some enthusiastic sole to repeat his work and publish it before we can ever know the true identity of the species hiding under this name.

A third species in the genus, Brachys aeruginosus, is smaller than either of the two above species – generally measuring only 3 to 4 mm in length.  This rather uncommonly encountered species is most similar to B. aerosus in appearance but can be distinguished, in addition to its generally smaller size, by the predominantly light gold to silver setae that cover the apical area of the elytra.  As with the two above species, it is most often associated with oaks but is occasionally collected on other hardwoods as well.  Whether it utilizes species beside oak for larval development is unknown.  I hope to find and photograph this species in the near future.

REFERENCE:

Anderson, D., C. L. Bellamy, H. A. Howden, and C. Quimby. 1991. George Britton Vogt (1920–1990). The Coleopterists Bulletin 45(1):93–95.

Copyright © Ted C. MacRae 2009

Add to FacebookAdd to NewsvineAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to Ma.gnoliaAdd to TechnoratiAdd to Furl

 

On the road again!

 

IMG_3397_0006_006_enh

By the time you read this, I’ll be on the road again for yet another extended bug collecting trip.  I don’t think I am ever happier than when I am on one of these trips – whether it be a once-in-a-lifetime visit to Africa or a one-week jaunt to the nearby plains.  With so many places to see – each with their own unique story – I don’t understand how anyone ever ends up getting bored.  The main destination for this trip is the Nature Conservancy’s recently established Four Canyon Preserve in northwestern Oklahoma.  This nearly 4,000-acre preserve contains a stunning assemblage of rugged, mixedgrass prairie ridges dissected by deep, chinquapin oak-lined canyons that drain into the Canadian River in southern Ellis County.  Although past grazing and fire suppression have reduced shrub cover, lowered vegetation complexity and promoted expansion of eastern redcedar (Juniperus virginiana) throughout the area, the preserve nevertheless supports a number of species of conservation concern such as Cassin’s sparrow, Swainson’s hawk, least tern, and Arkansas River shiner.

IMG_3285_0024_024_enh

As is typical with many protected areas, studies of the biotic diversity of this preserve have dealt primarily with its flora (Hoagland and Buthod 2007) and avifauna (Patten et al. 2006). Arthropods and other microfauna, on the other hand, remain essentially unknown.  I’ll be joining a group of entomologists – primarily hymenopterists – who began conducting surveys of the preserve’s insect fauna last fall.  While my colleagues gaze at the hyperdiversity of asteraceous flowers looking for things with stings, I’ll be staring at the red Permian sandstone and shale exposures – watching for any darting movement between clumps of grama and little bluestem that might indicate the presence of the enigmatic Cicindela celeripes (swift tiger beetle).  I’ve written previously about the occurrence of this rare, flightless tiger beetle in the Loess Hills of Iowa and our ongoing search for this species in northwestern Missouri in my post The Hunt for Cicindela celeripes.  Although this beetle has not yet been recorded at the preserve, it was seen very recently in nearby Alabaster Caverns – some 60 miles to the north, and a historical record is known from just south of the preserve.  My optimism is bolstered by the fact that the Alabaster Caverns individual was observed in late May – much earlier than the typical late June and early July records for this species further north in its stronghold in the Flint Hills of Kansas.  Of course, I will be looking for other things as well – other species of tiger beetles are likely to occur on the reddish loamy upland soils and quaternary alluvial deposits along the Canadian River, and any number of woodboring beetle species are likely to be found on herbaceous flowers and dead branches of the 51 species of woody plants recorded in the preserve.

After getting our fill of Four Canyon Preserve, we’ll visit the world’s largest remaining tract of tallgrass prairie, Tallgrass Prairie Preserve in northeastern Oklahoma.  Encompassing nearly 40,000 acres, we can do nothing more than only scratch its surface.  However, the tallgrass prairie habitat should provide a nice contrast to the mixedgrass prairie of Four Canyon Preserve, and it will be interesting to compare and contrast these two distinctive plant communities and their associated insect faunas.  After a week on the road¹, I’ll return to St. Louis for a brief respite before beginning a hectic four-week survey in northwestern Missouri for – you guessed it – Cicindela celeripes!

¹ I’ll be without internet access, so please forgive my nonresponsiveness to comments. I do have a couple of posts scheduled to appear during my absence.

My thanks to Mike Arduser, an expert hymenopterist and also a good friend, for bringing Four Canyon Preserve to my attention.  His spectacular photographs that I share here were all I needed to convince me to join him on his return trip this season.

REFERENCES:

Hoagland, B. W., and A. K. Buthod.  2007.  Vascular flora of the Four Canyons Preserve, Ellis County, Oklahoma.  Journal of the Botanical Research Institute of Texas 1(1):655–664.

Patten, M. A., D. L. Reinking, and D. H. Wolfe.  2006.  Avifauna of the Four Canyon Preserve, Ellis County, Oklahoma.  Publications of the Oklahoma Biological Survey (2nd Series) 7:11-20.

Copyright © Ted C. MacRae 2009

Add to FacebookAdd to NewsvineAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to Ma.gnoliaAdd to TechnoratiAdd to Furl

Goldenrod Leaf Miner

Microrhopala_vittata_IMG_0183_enh2

Photo details: Canon MP-E 65mm macro lens on a Canon EOS 50D, ISO 100, 1/200 sec, f/16, MT-24EX flash 1/8 power through diffuser caps

While photographing Acmaeodera tubulus and A. ornata a couple of weekends ago (see Springtime Acmaeodera), I came across this leaf beetle (family Chrysomelidae) of the genus Microrhopala¹.  When I took Systematic Entomology (so many moons ago), beetles in this and related genera were placed in the subfamily Hispinae.  That taxon has since been subsumed by a more broadly defined Cassidinae (Staines 2002), which also includes the delightfully odd tortoise beetles.  There are several species of Microrhopala in North America – this individual can be diagnosed as M. vittata by means of its dull reddish elytral stripes, eight-segmented antennae, and smooth (not serrate or toothed) elytral margins (Clark 1983). 

¹ Derived from the Greek micr (small) and rhopal (a club) – presumably a reference to its small-clubbed antennae.

Many leaf beetles are expert botanists, restricted to and able to discriminate a single plant species or group of closely related species for hosts.  Microrhopala vittata is no exception, specializing on true goldenrods (Solidago spp.) and flat-topped goldenrod (Euthamia graminifolia) (family Asteraceae).  Adults feed on leaves in the upper part of the plant, leaving numerous small holes, but it is the larvae that have the biggest impact on their host by mining within the leaves between the upper and lower surfaces.  Larval mining eventually causes the leaves to turn brown and shrivel up. 

This species has been widely studied by ecologists interested in understanding the impacts of herbivorous insects on their host plants and associated changes to plant communities that result from their feeding.  While population densities of M. vittata are normally low, they occasionally reach densities that result in severe damage to their host plants.  Such effects are not limited to the host plants themselves – Carson and Root (2000) found that outbreaks of this species on stands of tall goldenrod (Solidago altissima) in an old field dramatically reduced the biomass, density, height, survivorship, and reproduction of tall goldenrod, resulting in higher abundance, species richness, and flowering shoot production among other plant species as a result of increased light penetration.  Conversely, in experimental plots where the beetles were removed, tall goldenrod developed dense stands that inhibited the growth of many other plants.  These effects lasted for several years after the outbreak.  Thus, the beetle can act as a keystone species² in old field communities, indirectly promoting woody plant invasion and speeding the transition of the old field to a tree-dominated community.

² A keystone species is one whose impacts on its community or ecosystem are large and greater than would be expected from its relative abundance or total biomass (Paine 1969).  Popular examples include the beaver, which transforms stream communities to ponds or swamps, and elephants, which prevent grasslands from converting to woodlands through destructive tree removal.  In contrast, trees, giant kelp, prairie grasses, and reef-building corals all have impacts that are large but not disproportionate to their also large total biomass and, thus, are not considered keystone species.

REFERENCES:

Carson, W. P. and R. B. Root.  2000.  Herbivory and plant species coexistence: Community regulation by an outbreaking phytophagous insect.  Ecological Monographs 70(1):73-99.

Clark, S. M. 1983. A revision of the genus Microrhopala (Coleoptera: Chrysomelidae) in America north of Mexico. The Great Basin Naturalist 43(4):597-617.

Paine, R. T. 1969. A note on trophic complexity and community stability. The American Naturalist 103(929):91–93.

Staines, C. L. 2002. The New World tribes and genera of hispines (Coleoptera: Chrysomelidae: Cassidinae). Proceedings of the Entomological Society of Washington 104(3): 721-784.

Copyright © Ted C. MacRae 2009

Add to FacebookAdd to NewsvineAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to Ma.gnoliaAdd to TechnoratiAdd to Furl

Springtime Acmaeodera

Last weekend I mustered up the courage to begin experimenting with the 1-5X macro lens with my new camera. I had played around with it a little, trying to get a feel for finding the subject (it seemed hard) and the working distance (it seemed close). Really though, no amount of fiddling around could take the place of taking it out into the field and using it. I found some ideal subjects to experiment with – springtime Acmaeodera. With more than 150 species, this is one of the largest genera of jewel beetles (family Buprestidae) in North America. This genus is in terrible need of revision – new species continue to be recognized on a regular basis from the desert southwest and Mexico, where the group reaches its greatest diversity. Only a handful of species, however, are found in the eastern part of the U.S.

Acmaeodera_tubulus_IMG_0110_enh2

Photo details: Canon MP-E 65mm macro lens on a Canon EOS 50D, ISO 100, 1/200 sec, f/11, MT-24EX flash 1/8 power through diffuser caps

One of the most abundant and widespread of these is Acmaeodera tubulus (first two photos). Measuring only 5-7mm in length, it is among the smallest members of the genus and can be recognized by its black color with bronzy sheen and 8 (usually) small, yellow spots forming two longitudinal rows on each elytron. Adults of this species feed on the petals of a great variety of flowers – this individual was feeding on the petals of eastern beebalm (Monarda bradburiana). The larvae of this species are wood borers in twigs and small branches of various hardwood trees – I myself have reared it from dead branches of green hawthorn (Crataegus viridis), several species of hickory (Carya spp.), hackberry (Celtis occidentalis), honey locust (Gleditsia triacanthos), walnut (Juglans nigra), eastern hophornbeam (Ostrya virginiana), willow (Salix sp.), and slippery elm (Ulmus rubra).

Acmaeodera_tubulus_IMG_0123_enh2

Photo details: Canon MP-E 65mm macro lens on a Canon EOS 50D, ISO 100, 1/200 sec, f/11, MT-24EX flash 1/8 power through diffuser caps

While not apparent from these photos, adults in flight have the appearance of small bees. The elytra of all Acmaeodera are fused and do not separate during flight as in most other beetles, which in this small species results in a profile during flight similar to that of a small halictid (sweat bee). There is another species in Missouri (A. neglecta) that closely resembles A. tubulus but which can be distinguished by its larger punctures, duller surface, and the yellow spots of the elytra often longitudinally coalesced into irregular “C”-shaped markings on each side. Acmaeodera neglecta occurs primarily in the south-central U.S., and in Missouri I have found it most often in glade habitats.

Acmaeodera_ornata_IMG_0155_enh2

Photo details: Canon EF 100mm macro lens on a Canon EOS 50D, ISO 100, 1/200 sec, f/11, MT-24EX flash 1/8 power through diffuser caps

Another common (though much less so than A. tubulus), springtime Acmaeodera in the eastern U.S. is Acmaeodera ornata (last photo). This handsome species is distinctly larger than A. tubulus, usually around 8-11mm in length, and has a broader, more flattened appearance with a distinct triangular depression on the pronotum. The elytra have a bluish cast rather than the bronzy sheen of A. tubulus, and the spots on the elytra are smaller, more numerous, and more of a creamy rather than yellow color. No other species in the eastern U.S. can be confused with it, although there is a very similar species (A. ornatoides) that occurs in Oklahoma and Texas.

This species, too, is fond of a great variety of flowers – especially asteraceous species, with this individual photographed on the widespread (but unfortunately exotic) ox-eye daisy (Leucanthemum vulgare). The body is covered with numerous long, thin hairs which may function in pollination – enlarge the photo to see the large amount of pollen that has become trapped among the hairs of this individual. Despite its widespread occurrence across the eatern U.S., larval host records are almost non-existent for this species – limited to some very old (and not entirely reliable) reports of it breeding in hickory and black locust (Robinina pseudoacacia). I have not managed to rear this species yet, despite the large number of rearings I’ve done from a wide variety of woody species in Missouri.

Copyright © Ted C. MacRae 2009

Add to FacebookAdd to NewsvineAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to Ma.gnoliaAdd to TechnoratiAdd to Furl