Despite the fact that I have a beetle blog and Alex has an ant blog, it is the latter where the regular series Friday Beetle Blogging resides (hmm, I wonder if I should start a Myrmecine Monday series?). Alex has perhaps the best science-based entomoblog out there, so I’m thrilled to contribute today’s edition – check it out: Friday Beetle Blogging – the Swift Tiger Beetle.
Copyright © Ted C. MacRae 2010
In the early 1980s, I was a young, green entomologist, fresh out of school with a budding interest in beetle taxonomy, a zeal for collecting, and a desire to meet other like-minded individuals. Among the first collectors I had the good fortune to meet was Ron Huber, one of the country’s leading tiger beetle experts and co-founder of the journal CICINDELA (now 42 years as co-editor). Although my interests had by then already begun narrowing to woodboring beetles, I liked tiger beetles well enough and managed to secure from him a single specimen of what Erwin and Pearson (2008) would later dub the “Great Plains giant tiger beetle,” Amblycheila cylindriformis – the largest tiger beetle in North America. I don’t remember what prompted Ron to part with this spectacular specimen – perhaps it was the lone Proserpinus gaurae (Lepidoptera: Sphingidae) adult that I possessed, which I had reared from a field-collected larva around that time, or maybe Ron had such a nice series of the species that making the day of a young collector was in itself reward enough. While clearly a tiger beetle, it was still so different by virtue of its enormous size (the species ranges from 25-38 mm in length), somber coloration, small eyes, and strictly nocturnal habit. For much of the past 25 years, that specimen has sat in my cabinet amongst a small assortment of other, mostly mundane tiger beetles that I had opportunistically taken on my woodboring beetle-focused collecting trips. While I longed to someday see the species for myself, to do that would mean making a special trip out to the Great Plains – woodboring beetle desert that it is – during the middle of summer and stumbling through the prairie in the dark with a flashlight. Such an effort always seemed too great for the sole purpose of finding a single species, and not even a woodboring beetle at that.
Interests evolve, however, and while I still consider woodboring beetles to be my primary interest, tiger beetles have increasingly occupied my attention over the past several years. Contrary to woodboring beetles, the Great Plains are a mecca for tiger beetle diversity, and in recent years I’ve made a number of trips to Nebraska, Kansas, South Dakota, and Oklahoma specifically to look for them. Such was the case in June of last year when I went to the Glass Mountains in northwestern Oklahoma on a hunch and found Cylindera celeripes, Dromochorus pruinina, and a large tiger beetle larva that I just recently concluded must represent A. cylindriformis. I had been rearing the larva for a year by the time I figured out its identity, and when I did I sudden found myself facing a “perfect storm” – an upcoming holiday weekend, adults presumably in peak adult activity, and I knew exactly where to look for them. Impulsively, I decided to use my July 4th weekend to make the 525-mile drive from St. Louis to the Glass Mountains – this would give me 2 nights to look for them and still allow me to make it back to work on Tuesday morning. Anything else I could find during the day would be icing on the cake, but even if I found nothing, the chance to see A. cylindriformis in the wild seemed worth the gamble.
I made it to Joplin, Missouri near the Oklahoma border by midnight on Friday but awoke to threatening skies the next morning. The threat of rain became a promise as I drove further west, and by the time I arrived in Enid, Oklahoma – just 30 miles from the Glass Mountains – it was raining heavily. I stopped at a coffee shop to access Wi-Fi, and checking the radar showed a line of storms moving up through Texas and western Oklahoma into Kansas – sitting right over the Glass Mountains! The forecast gave no reason for optimism, with a 50% chance of thunderstorms through the weekend. Smartly, I had recorded the locality of the Huber-specimen – collected in northwestern Kansas – and checked the forecast for that area, but it was even worse (50% chance of thunderstorms through Sunday and 80% Sunday night). Clearly this was not good, but I had made the drive and was determined to make something happen. I decided the best thing to do would be to just continue driving west – however far that was – until I got past the storm system and see what was around – wherever that might be. I gassed up amidst a gusty, torrential downpour and headed west out of town. As I drove, the rain lightened up and eventually ceased. The roads were wet, but at least it wasn’t raining, and when I arrived at the Glass Mountains even the roads seemed to be drying. Winds were still strong, but the clouds had broken somewhat, allowing brief periods of sun to further dry things out, and what followed was a most fascinating day on top of one of the Glass Mountain mesas (highlights include C. celeripes, D. pruinina, Microstylus morosus, Trichodes sp. – look for these in future posts). As dusk approached I searched the grasslands below hoping to see a rattlesnake or two – I had seen a western pygmy rattlesnake here last year, and western diamondbacks are also in the area, but I saw none.
Of course, all this was really just passing time – waiting for nightfall and hoping the rain continued to hold off so I could begin searching the prairie down below for A. cylindriformis. It had sprinkled once or twice during the day, and I couldn’t tell if the darkening western sky was truly rain or the just the coming dusk. At 9pm, with darkness fast approaching, I set out with my headlamp and made a beeline for the native prairie habitat on the lower talus slopes where I had last year collected the larva and observed additional larval burrows that I took to be the same species. I must admit that the thought of walking alone through the prairie at night in western diamondback rattlesnake habitat made me more than a little nervous, and I kept just as much an eye out for them as I did the tiger beetles that I was looking for. As the night wore on, my hopes began to dim – I had searched for almost an hour and had covered most of the area where I had seen larval burrows last year. With no sign of the beetle, the negative thoughts started to enter my head – did I make this drive for nothing? How sure was I that the larva really represented Amblycheila? Did I have the right search image? I mean, they’re huge black beetles – they should be easy to spot, right? Oh great, I made all this fuss on my blog about looking for the species – how embarrassing to have to say, “Uhm, well, I didn’t find it.” Just as I began wrapping back around the bottom of the talus slope, there it was – no doubt about it! I just watched it for a while and noted that it moved with some urgency, but it was not the speedy, jerking walk of ‘regular’ tiger beetles – rather, it was more lumbering, seeming to pick each foot up rather high, like a cat with rubber bands on its feet (how would I know about that?). There seemed little risk of it escaping me, so I got out the camera and began following it to take photographs – no way! While it may have lacked the speed of other tiger beetles, it also lacked their propensity to occasionally pause long enough to allow a shot or two. Add the darkness, fear of rattlesnakes, and constant bumping of the flash unit on my headlamp, and it was soon apparent that getting good field photographs was going to be a low percentage proposition. I resigned myself to taking photographs later in a terrarium (several shown here) and spend my time in the field more productively looking for additional individuals.
Finding the first individual did wonders for my motivation, and though still nervous about the potential for rattlesnakes I continued searching an ever-widening swath of the talus slope and adjacent areas. Another hour passed, and I had searched not only the native prairie below the talus slopes, but clay exposures on adjacent somewhat altered habitat. Again, the negative thoughts started creeping back into my mind – am I really gonna walk away from here with a single individual? I can say I found it, but that was a long drive for one beetle! I continued searching along an adjacent drainage ditch, and by 11:30pm I conceded that my victory was small and walked back to the truck to get a container to fill with native soil for a terrarium. Though it was a bit of a walk back up to the talus slope where I had seen the larval burrows, I wanted to take soil from that area specifically to give myself the best shot at obtaining eggs from my single (hopefully female) individual for an attempt at rearing more specimens from larvae. As I approached the exact spot where I had collected last year’s larva, I saw another, even larger adult! I don’t know which was greater – my excitement at finding such a large individual, or my relief in knowing that I would not go home with only one. Of course, with the second individual came a new shot of motivation, so once again I scanned across the talus slopes, and during the next half hour I found two more very near to where I had found the second one. By then it was past midnight, so I set about the business of digging soil for the terrarium. I finished the job (getting stung something terrible by three red, big-headed ants that had crawled up my pant leg while I was digging), took one last sweep across the immediate area, and turned to walk back to the truck when I saw the biggest one of all – I later determined it to be a male measuring 35 mm in length (that’s just about an inch and a half, folks!). With five individuals now, the urgency to find more was gone, and I decided I’d done what I needed to do and should get into town and find a hotel room. As I walked back to the truck, rain began to fall – lightly at first but ever increasing. Once back at the truck it was raining persistently enough that I could only hurriedly take some quick photographs of the beetles in their terrarium as in situ documentation of the momentous occasion!
Occurrence of Amblycheila cylindriformis. White arrows indicate where adults were found, all of which were on red clay/gypsum exposures on lower talus slopes in native prairie habitat. No adults were seen in clay/gypsum exposures further below the slopes in either native (zone 1) or altered prairie (zone 2) or further down in roadside drainages (zone 3).
Although I had accomplished my main goal, I looked forward to the opportunity the next day to search for C. celeripes at other nearby sites to better understand the extent of the area’s population. Sadly, the rain that had held off for nine hours before returning just after midnight was back for good, with radar the next morning showing a broad swath of rain extending across the entire western part of Oklahoma and north into Kansas. There wasn’t much for me to do but savor the previous day’s experience while I made the 525-mile drive back east. This may represent a significant record for the species – Vaurie (1955) in her review of the genus did not see any specimens from Oklahoma (although she did examine a few specimens from adjacent areas of Kansas), and Drew and Van Cleave (1962) reported only a single specimen from the state in nearby Woodward County. Significant record or not, it was an experience that I’ll not soon forget.
Photo Details: Canon 50D (ISO 100, 1/250 sec), Canon MT-24EX flash.
Photos 1-3: Canon 100mm macro lens (f/14-20), flash 1/4 power w/ Sto-Fen diffusers.
Photo 4: Canon MP-E 65mm 1-5X macro lens (f/14), flash 1/8 power w/ Sto-Fen + Gary Fong Puffer diffusers.
Post-processing: levels, unsharp mask, slight cropping on photo 1.
Note to self: clean specimens with moist brush to remove dirt before photographing them!
REFERENCES:
Drew, W. A. and H. W. Van Cleave. 1962. The tiger beetles of Oklahoma (Cicindelidae). Proceedings of the Oklahoma Academy of Science 42:101–122.
Erwin, T. L. and D. L. Pearson. 2008. A Treatise on the Western Hemisphere Caraboidea (Coleoptera). Their classification, distributions, and ways of life. Volume II (Carabidae-Nebriiformes 2-Cicindelitae). Pensoft Series Faunistica 84. Pensoft Publishers, Sofia, 400 pp.
Vaurie, P. 1955. A review of the North American genus Amblycheila (Coleoptera, Cicindelidae). American Museum Novitates 1724:1–26.
Copyright © Ted C. MacRae 2010
The generous among us might call it serendipity, while the rest of us would just call it luck. By whatever name, I had it in spades in June last year when I made my first visit to the Glass Mountains of northwestern Oklahoma. My original plan was to go to Tallgrass Prairie Preserve in eastern Oklahoma at the end of what proved to be a resoundingly successful day at Alabaster Caverns State Park. However, soaking rains moved into the area and continued rumbling eastward across the plains towards the preserve, forcing a quick change of itinerary. I decided to wait it out in the state’s western reaches, a “hunch” telling me that the red clay/gypsum hills in nearby Major County might be a fruitful place for hunting tiger beetles. Sunny skies the next morning were a good sign, and my hunch was rewarded later that day when I discovered a previously unknown (and fortunately robust) population of the rare Cylindera celeripes (swift tiger beetle), making not just the day but the entire trip more successful than I could have ever imagined. Icing on the cake came when I found decent numbers of the more secure but nevertheless uncommon Dromochorus pruinina (frosted dromo tiger beetle) also in the area.
Another find I made that day that I’ve mentioned on occasion but not talked about at length was a single, rather large tiger beetle larva. I found several burrows at the base of a talus slope at the edge of a small ravine where many adult C. celeripes were scurrying, and though I tried with many, out of only one did I manage to “fish” its occupant with a blade of grass. I didn’t know which species it represented, but its large size and occurrence in clay soil brought to mind two species – Cicindela pulchra (beautiful tiger beetle) and C. obsoleta (large grassland tiger beetle). Both of these Great Plains species reach their eastern limit of distribution in this part of Oklahoma (Pearson et al. 2006), and their status as the largest species of the genus (and its former subgenera) in North America seemed to make them the leading candidates for this enormous larva. There was one other possibility – Amblycheila cylindriformis (Great Plains giant tiger beetle), another Great Plains species at its eastern limit in western Oklahoma and (as the common name implies) the largest tiger beetle in all of North America. However, to consider that species seemed too much wishful thinking. From my understanding, larvae of that elusive species reach an incredible 45 mm in length and dig burrows on steep slopes or at the mouths of rodent burrows that extend vertically to depths of up to 1.5 m or more (Brust et al. 2005). Surely I could not have so casually stumbled upon such a grand grub!
I placed the larva in a terrarium of native soil and brought it back with me, and for one year now I have waited – feeding it a regular diet of the fat noctuid caterpillars that we rear so abundantly in our lab. For a full year, I’ve watched it nab caterpillar after caterpillar, disappearing mysteriously for days on end, and just as mysteriously reappearing at the top of its burrow. I knew getting a closer look at it would help in my attempts to determine its identity, but every time I approached with a camera it dodged down into its burrow and beat my patience. Sometimes I would see it sitting about a centimeter below the burrow entrance – just waiting for a caterpillar to crawl by but refusing to expose itself to the lens. I gradually decided it was likely C. pulchra, as I had seen that species in similar habitat not too far north in Barber County, Kansas. So strong was my suspicion that I even made another trip out to the Glass Mountains in October of last year, expecting to see the fall-active adults bejeweling the exposed flats below the red clay slopes, their wine-red elytra and purple-margined bodies all aglitter under the crisp, autumn sun. No such sight was beheld, however – my hopes dashed by the season’s sudden cold and wet turn, and with the terrarium containing the larva by then tucked away in a cool incubator for a winter’s rest, it would be several months before I would see the larva once again sitting at the top of its burrow.
In late March I pulled the terrarium out of the incubator, and within a week the larva reopened its burrow. I fed it a few times, and then one day I saw that it had dug a new, larger burrow – measuring a full 10 mm in diameter! This seemed extraordinarily large for any species of Cicindela, so I resolved once again to photograph it and determine its identity. For days I stalked it, keeping the terrarium just outside my office door where I could keep an eye on it, yet every time I approached within two feet or so it would drop down out of sight. I decided to stop feeding it – perhaps hunger would overwhelm its patience and prompt it to return to the top of its burrow more quickly after retreating. That seemed to work, as one day the larva came back up after only a few minutes – and I was ready! Already in position, I flashed off multiple shots as soon as it reappeared, moving slowly and deliberately between shots to avoid spooking it again, and managed to get a nice series from varying distances. As a testament to its enormous size, all of the photos shown here were taken with the standard 100mm macro lens (1X maximum) – not the 65mm 1-5X beast that I needed for these shots of the super-tiny C. celeripes.
Thinking that the larva likely represented C. pulchra, I compared the photos to this photo taken by Matt Brust of a 3rd-instar larva of C. pulchra and immediately noted the differently shaped pronotum of my larva and its distinctly projecting anterolateral angles. Compare to C. pulchra, in which the angles are in line with the median part of the anterior margin – it is clearly not that species. It isn’t C. obsoleta either, as that species has the anterolateral angles of the pronotum even less projecting than C. pulchra (Drew and Van Cleave 1962). Apparently I needed to rethink my assumption that it belonged to Cicindela or its close relatives – none that occur in Oklahoma are simply large enough! Tetracha virginica is large enough, but I knew it wasn’t that species since it lacked the white margined pronotum distinctive of species in that genus (as can be seen in this post on the larva of Tetracha florida). That left only A. cylindriformis, distinguishable from all other tiger beetle genera occurring in Oklahoma by the second (lower) pair of eyes distinctly smaller than the first (Hamilton 1925, Drew and Van Cleave 1962, Pearson et al. 2006) – clearly seen in the third photo above. Matt Brust has also photographed the larva of A. cylindriformis – it’s not a close shot of the head and pronotum, but in general aspect my larva seems to match it well enough.
All that is left is to actually succeed in rearing this larva to adulthood. These beasts may require up to three to four years to develop (Brust et al. 2005), although this is likely influenced by latitude and prey abundance. I suspect it was a second instar larva when I collected it, and that it dug its new burrow this spring after molting to the third (and final) instar. Hopefully by keeping it in a nice, warm growth chamber and feeding it generously with fat caterpillars, I can minimize the time to pupation and perhaps see the adult sometime later this summer. If/when that happens, you can be sure to see a follow up to this post.
Photo Details: Canon 50D (ISO 100, 1/250 sec, f/16-18), Canon 100mm macro lens, Canon MT-24EX flash (1/4 ratio) w/ Sto-Fen diffusers. Post-processing: contrast and unsharp mask (no cropping).
REFERENCES:
Brust, M. L., S. M. Spomer and W. W. Hoback. 2005. Tiger Beetles of Nebraska. University of Nebraska at Kearney. http://www.unk.edu (Version 5APR2005).
Drew, W. A. and H. W. Van Cleave. 1962. The tiger beetles of Oklahoma (Cicindelidae). Proceedings of the Oklahoma Academy of Science 42:101–122.
Hamilton, C. C. 1925. Studies on the morphology, taxonomy, and ecology of the larvae of Holarctic tiger beetles (family Cicindelidae). Proceedings of the U.S. National Museum 65 (Art. 17):1–87.
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 2010
Sorry about the noisy video – it was shot in one of our walk-in growth chambers with fans going full-bore! Anyway, the video shows a couple of mating pairs of Cylindera celeripes (swift tiger beetle) that I brought back from the Loess Hills of extreme northwest Missouri this past weekend. Watch carefully and you’ll see the first pair actively copulating before they break apart. After that I pan over to the second pair, which is not actively mating but have remained coupled as an example of behavior called “mate guarding” You might also notice a few very small green “bugs” in the container – these are 2nd-instar Lygus nymphs, which I placed in the container earlier in the day as prey – it was quite a sight to see the tiger beetles immediately begin chowing down on them! At the end of the video, I poke at the second mating pair with my forefinger to give an indication of their tiny size – this flightless species is one of the smallest in all of North America! Knowing how tiny the beetles are and how well they blend into their surroundings (you’ll have to imagine the 1-2 ft of plant growth that was surrounding them in the field), you can appreciate just how difficult these beetles are to detect in their native habitat.
There is a “good news, bad news” aspect to the story behind these beetles. This rare Great Plains species was unknown from Missouri until last year, when we (Chris Brown and I) discovered it in loess hilltop prairie remnants at Brickyard Hill, Star School Hill Prairie, and McCormack Loess Mounds Conservation Areas. Loess hilltop prairie is among Missouri’s most critically endangered natural community due to its restricted occurrence at the southern tip of the Loess Hills landform and more than a century of overgrazing and relentless encroachment by woody vegetation and invasive exotics. The sites where we found the beetle last year contain the highest quality loess hilltop prairie remnants in Missouri, so we are now taking a more thorough look at some of the smaller remnants that still exist in the area. The most promising of these are at Squaw Creek National Wildlife Refuge and on several privately owned lands near the known sites, and these were the sites that I searched this past weekend. Some of these sites looked promising (one in particular looked excellent), but thorough searching at each revealed no beetles. By the time I finished searching the last of them I had begun to wonder if: 1) my “search image” for the species had gotten rusty, or 2) my timing was a bit too early (last year’s populations were discovered in late June). To test this, we (daughter Madison and I) returned to one of the known sites (McCormack) where we had seen only two beetles last year (unable to capture either one). As we hiked along the ridge top leading to the spot where we saw them, I kept a close watch on the narrow trail in front of me. Nothing. However, as soon as I came upon “the spot” I saw one! I dropped to my knees and slapped my hands down on the ground, forming an “arena” between my two thumbs and forefingers, but the beetle ran over my hand too quickly and escaped. No matter – in less than a minute I saw another one and successfully trapped it under my fingers as it ran over my other hand. During the next 15-20 minutes I would see at least eight individuals along the narrow trail in this single spot. While it was gratifying to see more individuals at this site than we had seen last year, it also meant that the timing of my searches at the other sites was fine and that I was not suffering from a rusty search image. The beetle could still be at those sites where I had failed to find it, but if it is then it certainly does not occur in very high numbers. It also bothers me that at this site the beetle seems to be restricted to one isolated ridge, which appears not to have been burned in recent years (in contrast to the rest of the preserve, which seems to have been burned within the past year or so). I searched all the remaining ridge top again thoroughly after finding the beetles again this year, but no beetles were seen anywhere except this tiny spot where we have now seen beetles in successive years.
Missouri’s few existing loess hilltop prairie remnants are not only small but highly disjunct, and the flightless nature of the beetle makes re-colonization of a remnant unlikely in the event of a localized extirpation. There is obviously much we still do not know about the impact of burning on the beetle and how best to devise management plans that consider both the habitat and the beetle. However, one thing is clear – both the habitat and the beetle are critically imperiled in Missouri, and the fate of both are in our hands, right here and right now! We’d better get this figured out quick if we’re going to save both, and there seems to be little room for error. For my part, in addition to pinpointing where our populations occur and precisely what habitats are supporting them, I am trying to develop an effective rearing technique for this never-before-reared species in the event that captive rearing becomes necessary for reintroduction or augmentation of native populations. The adults seem very delicate and do not travel well, but I have found that if I prepare a terrarium in the field for transporting the adults then they survive well – even when traveling for several days. The container measures 6 1/4” H x 8” L, and I’ve placed a chunk of native soil cut from the site where I found the beetles and kept intact. The debris on the soil surface is intact as well, but the plants growing in the soil have (obviously) been trimmed. I’ll collect eggs from these individuals and experiment with different methods that I’ve been working on for rearing the larvae to see which are the most efficient and effective.
Copyright © Ted C. MacRae 2010
…in the Loess Hills of northwest Missouri, looking for additional sites for Cylindera celeripes (swift tiger beetle). Recall that we (Chris Brown and I) finally found this rarely collected species last year in Missouri (after many years of looking) in high quality remnants of loess hilltop prairie (a critically endangered natural community in Missouri). The beetle was found at Brickyard Hill, Star School Hill Prairie, and McCormack Loess Mounds Conservation Areas, which combined contain nearly half of the 50 or so acres of loess hilltop prairie still existing in Missouri. The remaining acres are located at Squaw Creek National Wildlife Refuge and on private lands – my sincere appreciation goes out to Squaw Creek Refuge staff and three private landowners, who have all graciously extended to me (and my able field assistant Madison) access to the loess hilltop prairie remnants under their stewardship to better characterize the beetle’s distribution in the area. The sites I am visiting have varied burn histories, ranging from recent to 6 years or more since the previous burn, thus, I am also hoping to better understand the possible impact of prescribed burns on the species’ occurrence in loess hilltop prairie remnants. The beetle needs these remnants to survive, and prescribed burning is an important tool for helping to restore this natural community after decades of shrinkage due to woody encroachment. The trick will be to design management plans that accomplish these restoration objectives while at the same time minimizing possible negative impacts of the burns on existing beetle populations.
Copyright © Ted C. MacRae 2010
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
In a recent post, I provided the first ever glimpse of the previously unknown larva of Cylindera celeripes, or swift tiger beetle. This little-known flightless species is among the tiniest in North America (adults measure only 8 or 9 mm in length), and so far nobody has succeeded in rearing the species in the lab, or even finding its larva. As the photographs in that post showed, I am reasonably close to accomplishing that first goal, having successfully obtained a number of eggs from field-collected adults placed in a terrarium of native soil. I fed the subsequent larvae a diet of small rootworm larvae and Lygus nymphs before putting them to sleep for the winter in a cold incubator, and the larvae resumed activity when I pulled them out of the incubator 2 months ago. Since then, they have feasted heavily on small noctuid larvae that we rear in our lab, and now most of the dozen or so larvae have sealed their burrows – I presume for pupation before (hopefully) emerging as adults in the next few weeks.
Cylindera celeripes 3rd instar larva - USA: Oklahoma, Woodward Co.
There is more to the story, however. I had brought the adults back home in June 2009 from a population I found at Alabaster Caverns State Park in northwestern Oklahoma. This was a reasonably robust population – news enough for a species that has not been seen in good numbers for many years now, and my discovery of equally healthy populations at several other locations in the general area gives new hope for the long-term prospects of a species that some regard as a potential candidate for listing as an endangered species. It also gave me hope that I might be able to find the larva were I to return to the area in the fall. I also had a hunch that Cicindela pulchra (beautiful tiger beetle) could be found in the area, based on some very large larvae I found during that June trip, so in early October I made a quick return to northwestern Oklahoma to search for these two species. While it was too cold and wet to have any hope of finding Cicindela pulchra adults (I still think the species is there), it did not prevent me from realizing my other goal. May I present one of the first ever field-collected larvae of Cylindera celeripes!
Cylindera celeripes 3rd instar larva - closeup of hump on 5th abdominal segment with hooks to aid in securing the larva in its burrow
I found the larvae at Alabaster Caverns where I had found the adults earlier in June, and although the larval burrows were very small (only 2 to 3 mm in diameter), I knew what they were immediately when I saw them. As I had observed for the adults, burrows tended to be near the edges of barren patches of soil in proximity to vegetation and not out in the middle of the barren areas. This makes sense, considering where it would be more likely for prey to be encountered. Because the weather was cold and gray, I didn’t see (or expect to see) larvae actively sitting at the tops of their burrows, so I began “fishing” to see if I could yank a few from their burrows. I fished quite a few burrows for the first half hour or so, but none of my attempts were successful. I began wondering if the larvae were even active at all or if they had already entered hibernation for the upcoming winter. While I was fishing, I noticed that the burrows all seemed rather shallow – only about 6” or so (most tiger beetles, having larger larvae, dig burrows that are much deeper). This gave me an idea. I went back to the truck and retrieved a small spade that I carry in case… well, I’d never actually used it before. Anyway, I inserted a grass stem into a burrow and sunk the spade into the ground right next to it, making sure I got the spade at least as deep as the grass blade. I then removed the spade and sunk it into the ground on the other side of the burrow, then pried until the entire chunk of soil came up intact. With the bottom of the soil chunk exposed, I used my knife to carefully remove slivers of soil until I found the end of the grass stem that I had inserted into the burrow. Carefully removing the soil in this area revealed the larva in a side chamber at the bottom of the burrow. Success! I took many photos of that larva right then and there, and over the next hour or so collected several more larvae, all but one of which I presumed were 3rd instars. I packed each larva in its own small vial of native soil for the trip home, and although I have been attempting to rear them out for confirmation of their identity, there is little doubt that they do indeed represent this species.
Cylindera celeripes 3rd instar larva - that grotesquely beautiful head!
The photographs I’m showing here are not those first field photographs that I took when I first discovered the larvae. Looking at those photographs after I returned home, I was dissatisfied with the amount of soil and debris that covered the larvae – especially their grotesquely unique head and pronotum. Instead, I removed one of the larvae from its rearing tube and gave it a “bath” – brushing it with a fine camel-hair brush in a shallow dish of water – to clean it up for the photographs shown here. After the photo shoot, I sacrificed this larva for the collection – it will be the basis for a formal description of the larva of this species (along with examples of the 1st and 2nd instars that I had sacrificed from my rearing, not yet confident that I would succeed in getting any of the others to 3rd instar). The only thing I am waiting on before preparing that description is to see whether I actually succeed in rearing this species from egg to adult – stay tuned!
Photo Details: Canon 50D (ISO 100, 1/250 sec, f/13-16). Canon MP-E 65mm 1-5X macro lens, MT-24EX flash (1/8 power) w/ Sto-Fen diffusers. Typical post-processing (levels, unsharp mask).
Copyright © Ted C. MacRae 2010
These are two of the Cylindera celeripes (swift tiger beetle) larvae that I’m rearing. Note: nobody has ever reared this species before! Nobody has ever even seen its larvae (before now, that is).
These larvae hatched from eggs that were laid by adults I brought back from northwestern Oklahoma last summer. I placed the adults in a small terrarium of native soil – at first just to see if I could keep them alive, and then to see if I could get them to lay eggs. The adults lived for about 4 weeks, and a short time later larval burrows started appearing in the soil. I fed them once or twice a week by placing 2nd instar corn rootworm larvae in the open burrows or dumping Lygus nymphs into the terrarium and letting them catch them naturally. I wasn’t sure this was working, because as the summer progressed I saw fewer and fewer open burrows. By October, there were no open burrows, and I feared none had survived. Nevertheless, I placed the terrarium in a cool (10°C, or 50°F) incubator for the winter and pulled it back out in late March. Within one week ten larvae had reopened their burrows – I believe all but one of them are 3rd instars, which is the last instar before pupation, and since they have awoken they have fed voraciously on 3rd instar fall armyworm larvae, which I dangle above their burrow. I love watching them snatch the armyworm from my forceps and drag the hapless prey down into their burrow. I’ve already preserved examples of the three larval instars and will describe it shortly (although truth be told, the 2nd and 3rd instars are from larvae I found in the field – but that is a post for another day). However, I’m keeping my fingers crossed for the piece de resistance – successfully rearing the species from egg to adult!
Photo Details: Canon MP-E 65mm 1-5X macro lens on Canon 50D, ISO 100, 1/250 sec, f/13-16, MT-24EX flash 1/8 power w/ Sto-Fen diffusers.
Copyright © Ted C. MacRae 2010
Beetles In The Bush 