Return to Calico Rock

Sandstone glade | nr. Calico Rock, Arkansas.

Although western sand dune endemics were the top goals on my cicindelophilic wish list during last fall’s Annual Tiger Beetle Trip, I started the trip by leaving St. Louis in the most unlikeliest of directions—south! No, I wasn’t trying to get to Denver without having to drive the tedious stretch of I-70 through Kansas. Rather, I wanted to take advantage of the chance to witness active adults of the Missouri/Arkansas disjunct population of Cicindelidia obsoleta vulturina (prairie tiger beetle)—perhaps my favorite of all tiger beetle species—on the sandstone glades near Calico Rock in north-central Arkansas. Widely disjunct from the main population’s eastern limit of distribution in central Texas, I’ve seen them at many locations in the White River Hills of southwestern Missouri and adjacent Arkansas over the past ten years, but never in the area around Calico Rock where they are best known from the state. I already had precise localities where I knew I could see them, as I had found 3rd-instar larvae earlier in the year (some of which had already emerged as adults), so I wanted see them and document the range of variability exhibited by adults at this southeasternmost known extent of the disjunct population’s distribution.

Cicindelidia obsoleta vulturina | nr. Calico Rock, Arkansas.

Although the adults were not quite as numerous as I have found them at certain sites in Missouri, I had no trouble finding them once I got to the area where I had collected the larvae this past June. While showing Steve Spomer our Missouri population last year, he commented that our Missouri adults seemed much less flighty than adults he had seen at Calico Rock. I must say that I agree with him, as I found the adults much more difficult to photograph than those in Missouri. To be honest, I had to stalk nearly ten individuals before the male in the photo above finally allowed me to get close to him. When adults are numerous this is not a problem, but in this case every failed attempt required several more minutes of searching for the next subject. Eventually, however, I got my mojo and started having success with the photographs.

Unlike true spring-fall species, mating occurs in fall instead of spring.

In the main population, and like other members of the genus Cicindelidia, adults are active during the summer months and exhibit the classic “summer” species life history. The Missouri/Arkansas disjunct population, however, shows a phenologic shift in adult activity to the cooler fall months—perhaps in response to the generally droughty conditions that prevail during the summer in this part of the country followed by rains during late summer and into fall. (This is one reason why I think this population may be deserving of separate subspecific status.) In this regard they appear to be ”spring-fall” species, but their life history does not match true members of that group, which emerge during fall as sexually immature adults, hibernate during winter, and re-emerge during spring for mating and oviposition. Thus, one never sees adults of classic spring-fall species like Cicindela limbalis mating during the fall. In contrast, adults of this disjunct population emerge, mate, and lay eggs all during the fall before the onset of winter, then they’re done. The eggs hatch during fall and require another season or two to reach 3rd-instar and pupate during the summer for fall emergence.

Coloration likely functions in crypsis, as shown by this individual nestled in amongst moss and lichens.

When viewed as prepared specimens in a cabinet, C. obsoleta and its subspecies are among the most conspicuous of species due to their large size (in Missouri and Arkansas only Tetracha virginica is larger), olive green coloration, and bold white maculations. More than likely, however, the combination of color and markings serve a crypsis function in their native habitat. This is clearly evident with the individual in the above photograph, who had retreated to a moss- and lichen-covered rock crevice in his efforts to evade my lens. Squint your eyes a little bit, and he almost disappears! It must be similar for visually based predators such as birds and lizards.

On more open ground and from a lower angle, the beetle is much more visible.

This same individual, however, becomes quite visible when chased onto more open rock surfaces (and viewed more laterally than from above). It is common to see individuals out in the open such as this, but more often than not when alarmed they fly or run to less exposed areas, relying on their cryptic coloration to avoid detection. In fact, when I follow beetles that have evaded me to the spot where I am sure they must have landed, I often fail to see them even though I am looking almost exactly in the area where they are sitting until they start to crawl and their movement catches my attention.

A rather greenish individual tries to hide amongst lichens and shortleaf pine duff.

I have observed a great deal of variability in coloration and maculation at locations in Missouri, with individuals ranging from bright green to dull olive-green to dark green and even brown, and the markings ranging from complete to interrupted. I saw a similar amount of variability in the Calico Rock population, with the exception of brownish (which I have only seen at the northernmost localities in Missouri) and fully maculated individuals. Most of the Calico Rock individuals were dull olive-green, but the female in the above photo (trying to evade my attentions by hiding amongst lichens and pine duff) was as bright a green as I’ve seen in any individual.

A very weakly maculate individual.

As mentioned above, I didn’t seen any individuals that I would consider fully maculated, and several that I saw were more weakly maculated than any I’ve seen in Missouri. The female in the photograph above was the most weakly-marked individual that I saw, with the lateral and median bands greatly interruped—the latter nearly reduced to small discal spots.

A dark, almost blackish female.

While I did not see brownish individuals as I have seen at the northernmost localities in Missouri, I did see the occasional blackish individual—the one in the above photograph also exhibiting about the greatest degree of macular development that I observed among the adults seen. My impression now is that there are clinal patterns to the coloration and macular development in this disjunct population, with markings tending to be more developed in northern localities. With the specimens collected from this and the many other locations throughout the disjunct population’s range that I have now sampled, a more critical assessment of variability in this population may now be possible.

Beetle's-eye view of sandstone glade habitat.

It has become standard practice for me to photograph tiger beetle habitats whenever I can. However, I’ve become interested recently in trying to understand how tiger beetles perceive their own habitats. While this isn’t possible to know precisely, ground level photographs can provide at least a clue into seeing the world from a beetle’s eye. I almost find this perspective of the glade habitat more interesting than the human perspective shown in the first photograph.

The last sight that their prey sees.

There can be little doubt about what the beetles themselves look like from the perspective of their prey. The photograph above may not properly represent the image generated by an insect’s collective ommatidia, but it certainly must be just as frightening!

Copyright © Ted C. MacRae 2012

Two things I love about glades during fall…

…prairie dock (Silphium terebinthinaceum) in bloom…

Prairie dock (Silphium terebinthinaceum) in bloom | Caney Mountain Cons. Area, Ozark Co., Missouri

…and prairie tiger beetles (Cicindelidia obsoleta vulturina) on the prowl…

Prairie tiger beetle (Cicindelidia obsoleta vulturina) | Caney Mountain Cons. Area, Ozark Co., Missouri

On the last weekend of August I made another trip to the White River Hills of north-central Arkansas in a last gasp effort to confirm the occurrence in the area of the swift tiger beetle (Cylindera celeripes).  Records of this species include a single individual collected in 1996 at a site near Calico Rock, but two trips to the area this past June had already failed to reveal its presence.  I didn’t really expect that I would find it this time either, and such was the case.  However, what I was expecting/hoping to see was the beginning of the fall emergence of the prairie tiger beetle.  The Missouri/Arkansas disjunct population of this handsome species is perhaps my favorite tiger beetle of all, not only because of its good looks but because of the many spectacular fall collecting trips I’ve taken through the White River Hills to look for it.  In this regard I had success, although only two individuals were seen all day long.  The area around Calico Rock seemed dry, apparently having been missed by the thunderstorms that rolled through the area a week earlier and that would have surely triggered full bore adult emergence. 

Long Bald Glade Natural Area, Caney Mountain Cons. Area, Ozark Co., Missouri

The following day I returned to Caney Mountain Conservation Area on the Missouri side, where last fall I had finally found prairie tiger beetles after years of searching what must be the extreme northeasternmost limit of its distribution.  Fresh evidence of recent rains was seen, and accordingly the beetles were out in fairly decent numbers in the same area where I found them last fall.  I took the opportunity to photograph a few individuals (which I had not done last year) and then turned my attention to looking for other insects.  I had my eye out for the spectacularly beautiful bumelia borer (Plinthocoelium suaveolens) and eventually found one.  I hoped also to see the marvelously monstrous Microstylum morosum (North America’s largest robber fly), which I found at this site in 2009 as a new state record and was rewarded with two individuals (these will serve as vouchers for the state record, since I didn’t collect it in 2009).  Temperatures were rather warm and both of these latter species are traditional “summer” species; however, the presence of prairie tiger beetles, the tawny tinge to the prairie grasses, and the noticeably longer shadows under a deep blue sky told me that fall was, indeed, on the way.

Prairie tiger beetle (Cicindelidia obsoleta vulturina) | Caney Mountain Cons. Area, Ozark Co., Missouri

While prairie tiger beetles are (at least for me) the most iconic harbinger of fall in the White River Hills, another classic fall sight was the thick stands of prairie dock plants with their tall, bolting flower spikes.  In Missouri this plant serves as a larval host for the longhorned beetle Ataxia hubbardi.  In my early years of collecting in Missouri’s glades, I delighted in finding adults of these beetles clinging to the flower stalks during fall—presumably laying eggs from which larvae would hatch and bore down into the tap-root.  Although commonly regarded as a pest in sunflower in the southern Great Plains, individuals associated with prairie dock in Missouri’s glades seem different—smaller, narrower, and darker—than those found on sunflower and other more common hosts.  Additional material will be needed to make a final assessment on whether these individuals represent a distinct taxon; however, I have not been able to find this species on prairie dock in Missouri since I moved back to the state nearly 16 years ago.  The reason for this sudden disappearance remains a mystery, and perhaps it is purely coincidental that the Missouri Department of Conservation began managing all of their glades with prescribed burns during my previous 5-year absence from the state.  In the meantime, I will continue to examine prairie dock stems every fall in the hopes that once again I will find the beetles and be able to come to a decision about their taxonomic status.  Perhaps I should re-focus my efforts in “low quality” (i.e., never-burned) gladey roadsides rather than our state’s “high quality” (i.e., high floral diversity) natural areas.

Copyright © Ted C. MacRae 2011

Oedipodine Rex

Sandstone glade habitat for Trimerotropis saxatilis | vic. Calico Rock, Arkansas

Ever since my current fascination with band-winged grasshoppers (family Acrididae, subfamily Oedipodinae) began, I have been obsessed with photographing one species above all others—Trimerotropis saxatilis, the lichen grasshopper. Like most species in the group, lichen grasshoppers utilize an interesting survival strategy that I call “conspicuous crypsis”—the use of stunning colors and contrasting markings to help them blend into the mottled and variably-colored environments that they inhabit.  Lichen grasshoppers take this strategy to the extreme, culminating in some individuals with the most gorgeous shade of blue-green in perfect match to the crustose lichens that cover the rock outcroppings of their preferred glade habitats.  In my opinion, they are the kings of the oedipodines!  I have seen them before in past years in the igneous and sandstone glades that dot the Ozark Highlands of southern Missouri.  Crustose lichens abound in these acid environments, providing the perfect backdrop to make invisible these otherwise conspicuous grasshoppers. This past June during a couple of visits to a marvelous sandstone glade complex near Calico Rock in north-central Arkansas I got my wish, and shown here are some of my favorites from the many, many photographs I took during those sessions.

Trimerotropis saxatilis with classic lichen-green coloration.

Lichen grasshoppers are actually quite variably colored—not all individuals exhibit the green coloration for which they are so famous.  Despite this, they are the only member of the genus occurring in the eastern U.S. and, thus, are immediately recognizable.  While they are beautiful in all of their color variations, I cannot lie—it is the green individuals that I constantly find myself admiring the most.  While many other grasshoppers are green, only a handful (themselves members of the same subfamily) exhibit the same stunning shade of blue-green that this one does.  Add to that an abundance of black speckling and contrasting bands, and you’ve got one gorgeous grasshopper.  Yet, for all their overt beauty, they are absolutely impossible to see in their native habitat until they take flight when approached.  Fortunately, their escape flights are short and not terribly erratic—with a little practice it becomes rather easy to track them in flight (aided by their interrupted buzzing crepitation) and watch where they land.  They may not be immediately visible after landing, but with careful study of the landing area they are usually quickly relocated.  Once detected, slow deliberate movements are all that are needed to allow a close approach and a good look (and photographs if desired).

The stunning green contrasts starkly against a dark moss backdrop.

Of course, the problem with ‘conspicuous crypsis’ (or any form of crypsis, for that matter) is that it only works when in the right environment.  I chased the above lichen-colored individual onto this patch of dark moss while trying to photograph it, at which point it became overtly visible.

The mottling of the colors is almost as fascinating as the colors themselves.

As previously mentioned, lichen grasshoppers come in a variety of colors and shades.  While the green individuals may be the most stunning, I was captivated also by the below individual, darker brown and black, with the most beautiful, contrastingly colored orange eyes.  This individual may not blend in as well as the green individuals when sitting on lichen-encrusted rocks; however, its coloration and patterning seem perfectly adapted to the more barren, darkly colored rock exposures.  This helps explain why not all lichen grasshoppers are green—the rock exposures in the glades that they inhabit are not uniformly lichen-encrusted, but rather consist of both encrusted and barren expanses of rock, with diverse coloration being a result of multiple and sometimes conflicting selective pressures.

A darker brownish individual with spectacular orange eyes.

A third individual, shown in the photograph below, resembles the second in that it is more brown than green.  However, the base coloration is lighter with greater contrast to the dark bands.  Like the second individual the eyes are spectacular orange, but it also exhibits a green shading on the back of the head behind the eyes not seen in the second individual.

Another brownish individual, this one more contrastingly marked.

Not only did I find the adults, but I also found a rather young nymph that certainly represents this species (I’m guessing maybe 3rd instar based on the degree of wing pad development).  This nymph exhibits the same stunning green coloration that the first individual above shows, and its fortuitous occurrence on both lichen-encrusted and (relatively) barren rocks provide an excellent demonstration of the effectiveness of its coloration in achieving crypsis—now you see me…

The lichen-colored nymph is easily seen against barren rock...

…now you don’t!

...but blends in marvelously amongst the lichens.

Copyright © Ted C. MacRae 2011

Rearing the Prairie Tiger Beetle (Cicindela obsoleta vulturina)

A Prairie Tiger Beetle larva peers up from its burrow in rocky soil of a dolomite glade in the White River Hills of southwestern Missouri. The head of this 3rd-instar larvae is about the size of a pencil eraser.

I had so looked forward to the long Memorial Day weekend collecting trip – time of season and the weather were perfect, and it had been several years since I’d made a late spring swing through the woodlands, glades, and prairies of western Missouri. But after two fruitless days of searching for nearly non-existent beetles at Ha Ha Tonka State Park, Lichen Glade Natural Area, and Penn-Sylvania Prairie, I was faced with a choice: return home disappointed or try something completely different in an attempt to salvage the weekend.  I chose the latter.

A 3rd-instar Prairie Tiger Beetle larva extracted from its burrow. Total length is ~30mm.

What could be more different than the White River Hills of southwestern Missouri?  The deeply dissected dolomite bedrocks supporting xeric, calcareous glades, dry woodlands and riparian watercourses couldn’t be more different than the gentle, acidic sandstone terrain of those more northerly locations.  Its hilltop glades (“balds”) are the most extensive such system in Missouri, and I’ve already featured several charismatic insects from my travels last summer to this part of Missouri, including Megaphasma denticrus (North America’s longest insect), Microstylus morosum (North America’s largest robber fly), and Plinthocoelium suaveolens (North America’s most beautiful longhorned beetle).  One insect that I also wanted to feature from that area but that eluded me during last fall’s cold and wet collecting trip is the Prairie Tiger Beetle – Cicindela obsoleta vulturina.  This impressive species is highly localized in Missouri, occurring no further north and east than the White River Hills.  Moreover, the populations in this part of the state and across the border in Arkansas are highly disjunct from the species’ main population in the southern Great Plains.  Like a number of other plants and animals, the Missouri/Arkansas disjunct may represent a relict from the hypsithermal maximum of several thousand years ago, finding refuge in these rocky hills after cooling temperatures and increasing moisture caused the grasslands of today’s west to retreat from their former eastern extent.

The ''business end'' - four eyes and two enormous mandibles. The metallic purple pronotum is covered with soil.

Despite its restricted occurrence in Missouri, the species is apparently secure and occurs commonly on the many dolomite glades that are found in the area. I have records from a number of localities in the White River Hills, but the best populations I’ve seen occur at Blackjack Knob in Taney County.  Of course, I would have absolutely no chance of seeing the adults during this Memorial Day weekend – adults don’t come out until late summer rains trigger emergence in late August and early September.  It was not, however, the adults that I was after, for I had seen larvae of what I believed must be this species in their burrows during one of my visits to this location last summer.  Although I have collected several other species of tiger beetles in the area, I reasoned these larvae must represent C. obsoleta vulturina due to their rather large size (this species is one of the largest in the genus in North America) and because they lacked the white bordering of the pronotum typical of species in the genus Tetracha – the only other genus occurring in Missouri with species as large as this.  I had tried to extract some of the larvae for an attempt at rearing, but neither of the two techniques I tried (“fishing” and “jabbing”) had worked.  Fishing involves inserting a thin grass stem into the burrow and yanking out the larva when it bites the stem; however, I found the burrows of this species to angle and turn due to the rocky soil rather than go straight down for a clear shot.  Jabbing involves placing the tip of a knife at a 45° angle about 1″ from the edge of an active burrow, waiting for the larva to return to the top of the burrow, and jabbing the knife into the soil to block the larva’s retreat – a quick flip of the knife exposes the larvae, but in this case jabbing did not work because I always ended up hitting a rock and missing the larva before it ducked back down in the burrow.

Hooks on the abdominal hump of a 3rd-instar Prairie Tiger Beetle larva prevent it from being pulled out of its burrow by struggling prey.

I returned to the site where I had seen larval burrows last year and once again found them.  I tried fishing a few, though I knew this would be futile, then jabbing – again with no success, and then had an idea.  I went to the truck and retrieved a small trowel that I use to dig soil for filling rearing containers, then found an active burrow (larva sitting at the top, though dropping upon my approach) and got in position using the trowel as I would the knife.  I held the trowel firmly with both hands and placed my body behind it so I could use all my weight to force the trowel into the soil and past the rocks when the larva returned to the top of the burrow – worked like a charm!  After taking photographs of the first larva that I successfully extracted, I set to the business of collecting nearly a dozen more over the next couple of hours.  I then filled several containers with soil (using rocks in the larger one to create “compartments” to keep the larvae separated), poked “starter burrows” in the soil, and one at a time placed the extracted larvae in the burrows and sealed them in by pushing/sliding my finger over the hole.  I’ve found this is necessary to prevent the larvae from crawling right back out and digging a new burrow somewhere else – not a problem if there is only one larva in the container (although I prefer they use the starter burrows that I place at the edge of the container so that I can see them in their burrows to help keep track of what they are doing); however, in containers with more than one larva they will often encounter each other and fight, resulting in some mortality.  Larvae sealed in starter burrows eventually dig it open again but generally continue excavating it for their new burrow.  One larva was not placed in a rearing container – it was kept in a vial for the trip home, where it was dispatched and preserved in alcohol as a larval voucher specimen.

This male adult Prairie Tiger Beetle (emerged 10 weeks after collecting the larva) shows the dark olive-green coloration and semi-complete markings typical of the MO/AR disjunct population.

After returning to St. Louis, I placed the rearing containers in a growth chamber and monitored larval activity 2-3 times per week.  Whenever a burrow was opened, I would place a fall armyworm, corn earworm, or tobacco hornworm larva in the burrow and seal it shut.  Some burrows would be re-opened almost immediately and, thus, fed again, while others stayed sealed for longer periods of time.  Tap water was added to the container whenever the soil surface became quite dry – generally once per week, and by late July nearly all of the burrows were sealed and inactive. If these larvae did, indeed, represent C. obsoleta vulturina, then this would be the time they would be pupating.  On August 15 I had my answer, when I checked the containers to find the above male had emerged, and the next day two more adults emerged as well (including the female shown below).

This female adult Prairie Tiger Beetle emerged the same day as the male and shows slightly brighter green coloration.

I put the emerged adults together in the largest rearing container, and within minutes the male and one of the females were coupled. I’ve kept them fed with small caterpillars and rootworm larvae, and numerous oviposition holes were eventually observed on the surface of the soil in the container. In a few weeks, I’ll place this container in a cold incubator for the winter and then watch next spring to see if larvae hatch and begin forming burrows. If so, it will be a chance to see if I can rear the species completely from egg to adult and preserve examples of the younger larval instars.

Photo Details: Canon 50D (ISO 100, 1/250 sec) w/ Canon MT-24EX flash w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).
Photos 1-2, 5-6: 100mm macro lens (f/14-f/16).
Photos 3-4: 65mm MP-E 1-5X macro lens (f/14).

Edit 9/10/10, 6:30 pm: I checked the terrarium today and discovered 24 brand new 1st-instar larval burrows dotting the soil surface.  They are quite large already, almost as big as 3rd-instar burrows of the diminutive Cylindera celeripes.  I guess I’m surprised to see larvae hatching already, as I expected they would overwinter as eggs and hatch in the spring.  Now that I think about it, however, hatching in the fall makes sense, as this gives them an opportunity to feed some before winter sets in and also allows them to burrow for more protection from freezing temperatures.  I’ve dumped a bunch of 2nd-3rd instar Lygus nymphs into the terrarium for their first meal.

Copyright © Ted C. MacRae 2010

Rejoicing the end of summer

Russet browns of big bluestem (Andropogon gerardii) and Indian grass (Sorgastrum nutans) blend with still-green foliage in early autumn at White River Balds Natural Area in southwestern Missouri.

Last week I awoke to refreshingly cool temperatures for the first time in a long time – a brutal heat wave that had gripped the Midwest for some time had finally (if only briefly) passed. Missouri typically experiences substantial heat and humidity during the height of summer, a result of warm, moisture-laden air sweeping up from the Gulf of Mexico and over our mid-continental position.  The first cool snap in mid-August, however, usually marks the beginning of the end of protracted heat. High temps may return (and usually do), but they are intermittent and the writing is on the wall – summer’s end is near, and fall is on its way! For most of my life, the coming of fall has always been something to which I looked forward eagerly – it really is my favorite time of year.  I don’t just love fall, I adooore it!!!  As a result, I sometimes forget that not everyone shares my feelings, so when I mentioned to a colleague last week how excited I was that fall was on the way, I was a little surprised by her less-than-pleased reaction. Kids I can understand –  fall means a return to school and the end of fun and sun and no responsibilities.  However, for most adults, fall does not entail as dramatic a paradigm shift – we get up and go to work everyday regardless of the season. Indeed, to my colleague, fall was not dreaded so much for what it is but what it portends – winter! I convinced myself that if she was as interested in natural history as I, surely she would appreciate fall as a time of transition in the natural world.  This logic proved faulty, however, when just a few days later one of my favorite entomologist/natural historian bloggers voiced a similar lamentation.

Xeric calcareous prairie (''cedar glade'') in southwestern Missouri - habitat for Cicindela obsoleta vulturina.

That the charms of fall are not immediately apparent to everyone is beyond me.  Who in middle America doesn’t rejoice the end of long, sweltering days as they cede to the cool days of fall?  Who dreads the crisp, clean, autumn air and its pungent, earthy aromas?  Who doesn’t marvel as they watch the landscape morph from summer’s monotonous shades of green – its forests becoming a riot of red, orange, and yellow, its grasslands a shifting mosaic of tawny, amber, and gold, and in all places shadows cast long and sharp by a cool yellow sun riding low in a deep blue sky?  For the natural historian, fall offers even more than just these sensory gifts – it’s not the end of the season, but rather part of a repeating continuum that includes birth, growth, senescence and quiescence.  Plants that have not yet flowered begin to do so in earnest, while those that have shift energy reserves into developing seeds.  The spring wildflowers may be long gone, but only now do the delicate blooms of Great Plains Ladies’-tresses orchids rise up on their tiny spires.  Grasses also, anonymous during the summer, now reach their zenith – some with seed heads as exquisite as any summer flower.  Insects and other animals step up activity, hastily harvesting fall’s bounty to provision nests or fatten their stores in preparation for the long, winter months ahead.

Gypsum Hills in south-central Kansas. Habitat for Cicindela pulchra.

For myself, it is tiger beetles that are fall’s main attraction.  Yes, tiger beetles are out during spring and summer as well, but there is something special about the fall tiger beetle fauna.  Glittering green, wine red, and vivid white, a number of tiger beetles make a brief appearance in the fall after having spent the summer as larvae, hidden in the ground while feeding on hapless insects that chanced too close to their burrows, until late summer rains triggered pupation and transformation to adulthood.  As the rest of the nature prepares for sleep, these gorgeous beetles take their first, tentative steps into the autumn world for a brief session of feeding and play before winter chases them back underground for the winter.  Every fall for the past several years now, I have looked forward to the annual fall tiger beetle trip to see some of the different species and the unique landscapes which harbor them.  From the “cedar glades” of Missouri’s Ozark Highlands and Gypsum Hills of south-central Kansas, to the Sandhills of central Nebraska and Black Hills of South Dakota, I’ve acquired an even greater passion for a season that I already loved.  I’ll never forget the first time I saw Cicindela pulchra (beautiful tiger beetle) flashing iridescently across the barren red clay.  I still remember the excitement of seeing my first C. obsoleta vulturina launching itself powerfully from amongst the clumps of big bluestem. I recall my amazement at my first encounter with C. limbata (sandy tiger beetle) as it danced across deep sand blows, undaunted by scouring 30 mph winds.  No doubt I have many equally vivid memories awaiting me in the future, as I intend to keep the annual fall tiger beetle trip a long-standing tradition.  For this year, I’m hoping that C. pulchra and a few other species will reward a late-September drive to the Nebraska and South Dakota Badlands.  Whether they do is almost irrelevant – I love fall, and the chance to see new localities during my favorite time of year will be reward enough.

Copyright © Ted C. MacRae 2010

Friday Flower – Sedum pulchellum

I’m particularly enamored with glades, and after nearly 30 years of exploring Missouri’s Ozark Highlands, there aren’t many glades of any significance that I haven’t visited at some time or another.  However, during my mostly unproductive Memorial Day weekend collecting trip, I had a chance to visit Bona Glade Natural Area in Dade County for the first time.  Located in southwestern Missouri where the Ozark woodlands of the Springfield Plateau begin transitioning to the grasslands of the Great Plains, this small (20 acres) sandstone glade is noted as a station for the federally threatened and state endangered Geocarpon minimum.  I did not see this diminutive plant (sometimes called tinytim) during my visit, but I did see another pretty little succulent – Sedum pulchellum.  Also called widowscross, this plant belongs to the Crassulaceae – the same family as the familiar jade houseplant.

Although not nearly as rare as Geocarpon, widowscross is nevertheless somewhat restricted in Missouri, occurring primarily in the southwestern quarter of the state.  Throughout much of its range it is primarily associated with calcareous limestone glades, ledges, and outcrops (Baskin and Baskin 1977), but in Missouri it grows also on acidic chert and sandstone glades (Yatskievych 2006) – as is the case at Bone Glade.  I’ve not encountered this plant before, thus when I spotted this little stand with its profusion of brilliant pink blossoms, it immediately caught my attention.  A winter annual, this species prefers full sun and well drained, disturbed soils and apparently produces seeds quite prolifically when grown under the right conditions.  These features, along with its petite attractiveness, would seem to make it an ideal native alternative for succulent gardens.

Another, much less common sedum also occurs at Bona Glade, Sedum nuttallianum (Nuttall’s sedum).  This species is similar to S. pulchellum but can be distinguished by its smaller leaves and yellow blossoms.  It’s range is similar to that of Geocarpon, growing almost exclusively on chert and sandstone glades from southwestern Missouri and southeastern Kansas south to Louisiana and Texas.  I did not see this plant either – in fact, after finding this small stand of S. pulchellum I searched the entire glade rather thoroughly and did not see any other plants of that species either.

Photo Details: Canon 50D (ISO 100-200, 1/400-500 sec, f/5.6), Canon 100mm macro lens, ambient light. Post-processing: minor cropping, levels, unsharp mask.

REFERENCES:

Baskin, J. M. and C. M. Baskin. 1977. Germination ecology of Sedum pulchellum Michx. (Crassulaceae). American Journal of Botany 64(10):1242-1247.

Yatskievych, G. 2006. Steyermark’s Flora of Missouri, Volume 2. The Missouri Botanical Garden Press, St. Louis, 1181 pp.

Copyright © Ted C. MacRae 2010

Email to a friend

Are we loving our prairies/glades/woodlands to death?

I had such high hopes for last weekend’s collecting trip – late May is boom time for insects across Missouri, we have had good moisture this spring, and I would be visiting some high-quality natural communities that I had not visited for a long time.  My stated goals (the jewel beetles, Agrilus impexus and A. frosti) were long shots – I knew that and would have been fine coming home without those species (which I did) had the the collecting been otherwise productive (which it was not).  Still, I’ve been doing this for a long time now, and I’ve learned to draw on my accumulated experience when things don’t go as planned to give myself the best shot at turning a bad collecting trip into a decent one when things don’t go as planned.  The itinerary with which I start is rarely the one that I actually follow, and this past weekend was a good example of such.

My first stop was Ha Ha Tonka State Park, one of Missouri’s premier parks, boasting high-quality chert, dolomite, and sandstone savanna interspersed with dolomite glades.  It is on these glades and savannas that I hoped to find Agrilus impexus, or failing that at least collect a nice diversity of other jewel beetles on the oaks and hickories of the savannas and surrounding woodlands.  However, it was with some reservation that I even came here after being told by my colleague at the Department of Natural Resources just 2 days before my trip that 75% of the park’s grasslands and woodlands had been burned within the past two years.  For an insect collector, this is never good news – in all my years of collecting insects, my experience in relatively recently-burned habitats has been consistent: collecting sucks!  I decided, however, to visit Ha Ha Tonka anyway because of the quality of the natural communities it contains, thinking perhaps I might be able to find pockets of unburned habitat supporting good insect populations.  This was not to be. I beat oak after oak in the savannas and woodlands – nothing!  I swept little bluestem and Indian grass in the glades – nothing!  The foliage was lush and green and the savanna and glade landscapes highly diverse – given the time of season the place should have been teeming with insect life, yet it almost seemed sterile. Were it not for a few Chrysobothris quadriimpressa jewel beetle adults that I found attracted to a recently wind-thrown black oak tree, I would not have seen any insects here at all.  It appeared my fears about park-wide depression of insect populations had been realized.  However, not one to waste a visit I decided to explore some of Ha Ha Tonka’s fascinating geological features.  Ha Ha Tonka contains one of Missouri’s best examples of karst geology, with complex structures formed from the collapse of a major cave system.  The Devil’s Promenade is one of the more spectacular examples of such, its horseshoe-shaped cliff representing the former interior walls of a now-collapsed cave.  As dusk approached, the day’s poor insect collecting caused me to abandon my plans to stay here and blacklight for nocturnal beetles.  Instead, I decided to break from the itinerary, drive further west and explore Lichen Glade Natural Area in the morning before heading to the Penn-Sylvania Prairie BioBlitz later that afternoon.

Devils Promenade, Ha Ha Tonka State Park

Lichen Glade Natural Area is a small area owned by The Nature Conservancy that boasts a high-quality sandstone glade surrounded by post oak/black jack oak forest.  My first visit to the area more than 20 years ago was during May, and it was one of the most productive collecting trips I’ve had with a number of Agrilus spp. (including A. frosti) beaten from post oak (Quercus stellata) along the woodland edge.  I didn’t visit again until fall of 2002, when Chris Brown, Rich Thoma and I found claybank tiger beetles (Cicindela limbalis) sunning on the exposed sandstone outcrops, and I made one more visit the following May to beat more insects off of post oak.  The Lichen Glade that I returned to this past weekend was a very different place from when I last visited – the surrounding woodlands had been extensively opened (I would guess within the past few years based on the size of the post oak resprouts), and fire had been used throughout the area.  Anticipation turned to frustration when no amount of beating of the woodland vegetation and sweeping of the glade vegetation turned up beetles in any appreciable numbers (or any insects for that matter) and two hours worth of effort yielded not a single buprestid beetle!

Sandstone glade community, Lichen Glade Natural Area

With resignation, I headed on over to Penn-Sylvania Prairie, where during the introduction to the BioBlitz I learned that nearly half of the 160-acre prairie was burned last December and all of it had been burned within the past few years.  I knew what I was going to find – nothing!  Okay, I shouldn’t say nothing, as there actually were some beetles present.  However, the numbers and diversity were low, with all of the species encountered representing common, widespread species.  Moreover, it was not just beetles – all of the invertebrate group leaders (which included experts on snails, ants, butterflies, and bees) reported low overall abundance and diversity in their groups of interest.  Only the vascular plants – the metric by which the value of prescribed burning is always assessed – showed high diversity, with 300 species of mostly native prairie plants recorded for the site.  It was a fun event, with probably ~75 attendees and a delicious pot luck dinner that evening; however, it would have been more enjoyable had there actually been a nice diversity of insects present to document for the preserve.

My comments may make it seem that I am against the use of prescribed burning.  This is not true - I understand the critical role that fire as a management technique plays in restoring and maintaining examples of Missouri’s historically fire-mediated landscape. Without fire and other processes to mimic natural disturbance factors, most of Missouri’s historical grasslands and woodlands suffer relentless encroachment by woody vegetation. However, the modern landscape is very different from the historical landscape, where fires of unpredictable scale, intensity, and frequency operated within a vastly larger scale to create a shifting mosaic of natural communities in various stages of ecological succession. Such processes cannot be recreated on today’s severely fragmented landscape, where the precious few remaining tracts of native habitat are relatively to extremely small and more often than not separated from each other by vast expanses of homogeneous and “inhospitable” habitat (e.g., agricultural, urbanized, or severely degraded lands).  It is in that context that I have great concerns about how aggressively fire has been used in recent years on our state’s natural areas and the impact this is having on insect populations – specialist and generalist alike.  Fire proponents will point to published studies that show little to no effect by the use of fire for managing small, isolated remnants on specialist insects (see review in Henderson 2010).  However, there are an equal number of studies that suggest such concerns are well-founded (see review in Panzer 2002). A consistent limitation in all of the studies that have been conducted is the lack of very large and long un-burned remnants.  Prescribed burning has been adopted so rapidly and pervasively that there just aren’t any significant un-burned remnants left to properly include as controls in such studies.  As a result, the insect fauna present at a given site at the start of such a study is already skewed towards those species that successfully recolonized the area post-burn.  At a minimum, the data to this point are inconclusive, and certainly the potential for impacts has not been given the consideration it warrants in designing fire-management plans for our own state’s prairies and glades. Furthermore, as rapidly and aggressively as fire has been adopted on our few, small, widely disjuct remnants, the opportunity for proper investigation of those potential effects may be gone.  A particularly egregious example of the lack of consideration being given to prairie invertebrates in designing fire management plans is shown in these photos of Iowa’s Sylvan Runkel State Preserve before and after a late May burn and the impact of that burn on a resident population of Nevada buck moths (Hemileuca nevadensis).

Here in Missouri, as in Iowa, it’s a problem of scale – the landscape is too fragmented and remnants too disjunct to manage based strictly on floristic response.   Populations of generalist insect species will recover, and even specialist species may be able to overcome such management practices if they are widely distributed and sufficiently mobile. But what about conservative species with low vagility, such as the swift tiger beetle (Cylindera celeripes) and our disjunct population of the frosted dromo tiger beetle (Dromochorus pruinina), flightless species restricted in Missouri to the few tiny remnants of loess hilltop prairie in northwestern Missouri and a single 2.5-mile stretch of roadside habitat in west-central Missouri?  Until directly relevant data, gathered here in Missouri, are forthcoming to suggest otherwise, I believe the most judicious use of fire possible should be practiced in restoring and maintaining our grasslands and woodlands.  In-season burns may have been a part of the historical landscape, but their use today has great potential to result in local extirpations and should be used only after the most careful consideration.  Leaving un-burned refugia within remnant habitats to accelerate recovery would also be prudent – yet many land managers disregard this practice because of its logistical difficulties. This is especially true in small parcels, yet it is precisely these remnants that have the most to gain from their use (or lose from not doing so!).  In the historical landscape, every burn was a patch burn – no matter what its size, there were always adjacent or proximal unburned habitat from which recolonization could occur.  Elk and bison, too, were integral components of the presettlement prairie landscape – their roamings caused intermittent, localized disturbances that were likely not only crucial to the tiger beetles that I study but may also have contributed to vegetational diversity through patch succession.  Techniques that mimic these natural disturbance factors include mowing, haying, and managed grazing.  They can be utilized to mimic those disturbances as well as delay woody encroachment, and their use in land management should be considered for their ecological value rather than deprioritized because of their relatively greater complexity and cost to implement. Mechanical removal and selective use of herbicides offer additional tools for addressing woody encroachment while minimizing potential impacts to insect populations. An effective management program that considers all of the flora and fauna of a remnant may not be possible unless all of these management tools are utilized, or at least properly considered. As my good friend James Trager said in a recent email (quoting Andrew Williams), habitat restoration ”cannot rest on any single management practice, nor practicing it too extensively.”

REFERENCES:

Henderson, R. A.  2010. Influence of Patch Size, Isolation, and Fire History on Hopper (Homoptera: Auchenorrhyncha) Communities of Eight Wisconsin Prairie Remnants.  Wisconsin Department of Natural Resources, Research Report 189, 22 pp.

Panzer, R. 2002. Compatibility of prescribed burning with the conservation of insects in small, isolated prairie reserves. Conservation Biology, 16(5):1296-1307.

Copyright © Ted C. MacRae 2010

Email to a friend

Long Weekend Bug Collecting Trip!

On Saturday, I’ll be joining a number of other Missouri biologists as a Group Leader for a BioBlitz at Penn-Sylvania Prairie (“C” on the map above).  Penn-Sylvania Prairie is a 160-acre tract of native tallgrass prairie in southwestern Missouri owned by the Missouri Prairie Foundation. I’ll be leading the “Beetles” group (of course), and as far as I can tell there has been little to no work done to survey beetles in this prairie.  Late May is an awesome time to look for beetles in southwestern Missouri, and with the forecast calling for sunny skies with highs in the mid-80′s, what better opportunity to add an extra day to an already long holiday weekend and do a…

Long Weekend Bug Collecting Trip!

View Larger Map

The BioBlitz is not until Saturday afternoon, so I’ve padded the itinerary with a few nearby southwestern Missouri spots that I’ve wanted to visit for some time now.  The first stop will be Ha Ha Tonka State Park (“B”) and its mosaic of dolomite glades and post oak savanna.  My interest in this area stems from two jewel beetle specimens collected there by a student at the University of Missouri, who gave them to me for identification.  These two specimens caused a stir when I first saw them, as I could not definitely ID them – they resembled Agrilus impexus, a common inhabitant of the desert southwest and Mexico, but they were much larger and, of course, were found in Missouri.  These specimens played a key role in clearing up a case of taxonomic confusion on the identity of Agrilus impexus when I sent them to U.S. Agrilus-guru Henry Hespenheide.  Through comparison with type specimens, he determined that these were among a smattering of specimens collected across the Great Plains that represent the true A. impexus, while the common southwestern U.S. species to which the name had long been applied was actually an undescribed species.  He described the latter as Agrilus paraimpexus (Hespenheide 2007), and the true A. impexus remains rare and little known.  Obviously, my two specimens are the only ones known from Missouri, and indeed only one other specimen of this species has been collected in the past 60 years!  I know that makes finding it a long shot, but the student who collected them told me he swept them from woody vegetation along the edge of a glade at Ha Ha Tonka Savanna Natural Area.  I suspect they may be associated with honey locust (Gleditsia triacanthos), thus, I will have my beating sheet and will be beating lots of honey locust on Friday – wish me luck!

On Sunday, I’ll work my way slightly northeast to some of the sandstone glades that are found in St. Clair Co. where the Osage Plains to the west transition into the Ozark Highlands to the east.  The two most interesting of these are Lichen Glade Natural Area (“D”) and Dave Rock Natural Area (“E”).  Here, sandstone glades and bluffs are surrounded by dry and dry mesic sandstone woodlands dominated by post oak (Quercus stellata) and blackjack oak (Quercus marilandica).  Many years ago, I beat a single specimen of Agrilus frosti off of post oak at Lichen Glade.  I have not collected the species since, and I know of only one other Missouri specimen collected by state agriculture personnel in a malaise trap in central Missouri.  I also hope to photograph the lichen grasshopper (Trimerotropis saxatilis), which I have seen commonly at both of these sites.  This Great Plains species is at its eastern limit of distribution in Missouri, occurring exclusively on sandstone and igneous glades where its cryptic coloration makes it nearly invisible against the acidic, lichen-covered rocks that dominate these habitats.

Otherwise, I have no specific goals for the trip, but as late May is prime time in this area for jewel beetles, I’ll be doing lots of general beating on the oaks and hickories that many species in this family favor as hosts for larval development.

REFERENCE:

Hespenheide, H. A.  2007. The identity of Agrilus impexus Horn, a new species, and taxonomic notes and records for other Agrilus Curtis species (Coleoptera: Buprestidae).  Zootaxa 1617:57–66.

Email to a friend