plains

Rattled in the Black Hills

/ Ted C. MacRae / 11 Comments

My first day in the Black Hills of South Dakota was spent at McNenny State Fish Hatchery near Spearfish – on the north side of the Black Hills. I went to this place on the advice of my esteemed colleagues in Nebraska, who suggested that I might be able to find several interesting tiger beetle species there: the closely related trio of beauties C. denverensis (green claybank tiger beetle), C. limbalis (common claybank tiger beetle), and C. splendida (splendid tiger beetle) in the red clay eroded banks; C. fulgida (crimson saltflat tiger beetle) and C. tranquebarica kirbyi (oblique-lined tiger beetle) around the lakes; and – again, if I’m lucky – intergrades between the prairie and boreal long-lipped tiger beetles (C. longilabris x nebraskana) along a trail through the shortgrass prairie east of the hatchery. For the first time since Saturday, I awoke to baby blue skies which filled me with an optimism and anticipation that made the 3-hour drive from Chadron, Nebraska to Spearfish, South Dakota seem interminable.

What my esteemed colleagues failed to include on that list of species I might encounter was Crotalus viridis – the prairie rattlesnake! Now folks, I’ve seen a number of rattlesnakes before – mostly in Texas – but I’ve never heard this sound in real life, much less heard it coming from a rattlesnake poised to strike. I encountered this fellow in the eroded red clay slopes above the lake, and even though I wasn’t too terribly close it gave me quite a start (my bravery in taking this photo is vastly exaggerated by the twin miracles of telephoto and cropping!). I walked a little more cautiously afterwards but gradually let my guard down over time. About an hour later, I was startled again by another rattler – I had come within 2 feet of it before it started rattling. I nearly jumped out of my skin, and once I got my heart stuffed back down my throat I noticed several dark juveniles coiled up with her. They slunk away, and I tiptoed back to the car having had my fill of the red clay slopes for the time being.

I did manage some success on the slopes before the rattlers drove me away – not with the claybank and splendid tigers that I had hoped to find, which were largely missing in action save for two individuals of C. limbalis that I spotted amongst the annoyingly similar appearing and ridiculously numerous C. purpurea audubonii (clay path tiger beetle). Success instead came in the form of this cerambycid beetle – Megacyllene comanchei. Recently described from Texas, nothing more was published about this species until I recorded a northern range extension into south-central Kansas (MacRae & Rice 2007). Its occurrence in the Black Hills is not only a new state record for South Dakota but also represents an incredible 700-mile northern range extension – on top of the previous one! Actually, Matt and I each found one individual a few days ago in Sioux County, Nebraska (also a new state record) – I had thought of this species at the time but decided I must be wrong and that I should wait until I got back before making an identification. But the capture of these three additional individuals even further north renewed my suspicions, and consultion of my databases shows good agreement with this species – note the white rather than yellow antemedian elytral band and medial portion of the postmedian elytral band, along with the medial and lateral coelescence of the apical and subapical bands, which distinguish this species from the closely related M. angulifera. The records from this trip show that M. comanchei is much more widely distributed than previously thought. Curiously, all five of the individuals I’ve seen (so far!) were crawling on the ground – an unusual habit for Megacyllene, which are normally found on flowers of goldenrod. The type series was associated with plants in the genus Heterotheca, which I did note growing in the area.

After escaping the snake slopes, I began surveying the lake margins to look for potential tiger beetle habitat. I was especially interested in C. fulgida – Matt and I had seen a single individual along a dry salt creek in Sioux County. The lakeshore around the upper lake was completely surrounded by thick vegetation – no tiger beetles there, but when I arrived at the lower lake I found some small areas of open ground along one side. They didn’t look very extensive, and my initial search of the area showed no activity. Closer inspection, however, showed the presence of larval burrows, and when I grabbed my fishing gear (the nearest grass stem) I promptly managed to extract a couple of larvae. Okay, so there are tiger beetles here, but which one I don’t know – probably C. tranquebarica kirbyi, which we had seen rather commonly at the same dry salt creek in Sioux County. Although the sun would not set for another two hours, it was quite cool already. I wondered if maybe the adults had already started digging in for the night and began looking for evidence of adult burrows. I looked carefully along the edge of the grassline when I saw movement – it was the back end of an adult C. fulgida kicking dirt out as it excavated its burrow. Success! I dug it out, took a few photos (one shown here) and started looking for similar appearing burrows. I not only found several more C. fulgida in their burrows, but also several C. tranquebarica kirbyi. The larvae I collected may or may not represent one of these species – there are other species associated with alkaline habitats that active at other times during the season. I collected a few more larvae, filled a container with soil from the spot – cutting out a section of salt-encrusted surface to place on top, placed all of the collected larvae in it, and watched them immediately start digging new burrows with their shovel-like heads. More babies to take care of!

With tiger beetle success under my belt and the sun setting fast, I decided the day was done and packed up the car. As I was closing the hatch, I happened to look over and saw something of great interest – milkweed! I had, in fact, been looking for milkweed all day long in the hopes – faint, I thought – of encountering the newly described Tetraopes heutheri (Skillman 2007). Mirror Lakes, at the McNenny Fish Hatchery, is the type locality of this species, and although the type series was collected in August I held out hope that the adults might persist until September. These hopes faded quickly, however, as I located milkweed plant after milkweed plant on the shortgrass prairie above the eroded clay slopes – all completely senesced, with nary a sign of any milkweed beetles. The plant I’d just spotted – only a small sprout – was green, and on it were two milkweed beetles! I excitedly took some pictures, then started looking carefully about and found several more on additional small sprouts in the area. Apparently, the sprouts represented regrowth from late-season mowing of the roadside, as several full-sized, completely senescent plants were found in the adjacent unmowed area. My excitement at having “found” T. heutheri (because of their small size and occurrence at the type locality) was short lived – closer examination of the specimens after returning home showed them to be very small individuals of the more common Great Plains species T. femoratus. I did have some doubts when I found the beetles, since the milkweed species on which I found them is not the same species with which T. heutheri was associated (Asclepias verticillata, a small species with narrow, linear leaves).

Day 2 in the Black Hills was spent at nearby Boundary Gulch, just across the border in the northeast corner of Wyoming. This was another attempt to find the C. longilabris x nebraskana intergrades that eluded me at McNenney, and although I failed to find them at this location also, I did find five other species of tiger beetles, including several beautifully marked C. limbalis to go along with the two I found the previous day. After that it was some spurious collecting here and there – including larvae from two spots in the southern Black Hills – as I traveled back to Chadron, Nebraska for the night. On tap for tomorrow – Nebraska’s famed Sand Hills! The beautiful sandy tiger beetle (C. limbata) – vivid white and iridescent green to red – hopefully will be found among the super abundant festive (C. scutellaris) and big sand (C. formosa) tigers, and I’ll get another shot at seeing the C. lengi (blowout tiger beetle) that I missed a few days ago.

Goin’ fishin’

/ Ted C. MacRae / 7 Comments

For the past two days I’ve been in Sioux County, Nebraska – just east of Wyoming and just south of South Dakota. As I traveled up through the western panhandle to arrive at this spot, I was pleasantly surprised by the varied terrain – not at all the monotonously flat landscape that I expected. The landscape in this so-called Pine Ridge area is even more surprising – an impressive escarpment drops 1,400′ from the high shortgrass prairie down to an eery badlands below. The escarpment itself is forested with Ponderosa pine and is studded with numerous impressive buttes. The photos shown here were taken in Sowbelly Canyon – typical of the landscape along the escarpment – and in the badlands below Monroe Canyon a little further west.

Enough about pines and buttes – my business here is tiger beetles. I met up yesterday with tiger beetle aficionado Matt Brust, who recently took a position here at Chadron State College after finishing his Ph.D. in Lincoln. I’ve been corresponding with Matt for a bit now, and when I told him of my interest in doing a tiger beetle trip through western Nebraska, he was more than willing to show me around and hopefully help me find some of the more unusual species I was looking for. Of course, tops on the priority list was Cicindela nebraskana (prairie long-lipped tiger beetle). This beetle isn’t common anywhere within its range and just sneaks into the northwest corner of Nebraska, where the type locality is located. Until recently, the species was known from very few specimens in Nebraska. Matt did some intensive sampling a few years ago and located a few limited populations in the vicinity of the type locality. Yesterday, he took me to two of these localities, and we succeeded in finding one individual at the first and several at the second. It was at the type locality where I succeeded in getting this field photo. While admittedly harshly-sunlit, it is as far as I know the only field photograph of the species – all others that I’ve seen have been taken in terraria. I’ll fix it up a bit with Photoshop and re-post once I get back home. This species looks similar to the black morph of Cicindela purpurea audubonii, which co-occurs with C. nebraskana in Nebraska, but it lacks the bright white labrum and elytral markings of the former. Also, as I would learn during these past two days, it can be instantly recognized in the field by its shinier appearance and “stubbier” legs. A few days before my arrival, Matt succeeded in finding the species in the next county to the east, an eastern range extension of about 60 miles, and today I located the species at another new locality between the two. It is gratifying to have played a small role in increasing our knowledge about this unusual species.

My success with C. nebraskana has come despite uncooperative weather. A series of frontal systems has moved through the area since my arrival, resulting in several rain events and lots of cool, cloudy weather. Tiger beetles are sun-loving insects, and when it gets too cold or wet the adults dig in and don’t come out until the sun shines through or temps warm enough to trigger them to dig out. Matt had taken me to another locality – a sand embankment – where we might find the beautiful Cicindela lengi (blowout tiger beetle), but it rained prior to our arrival and we saw no activity. I tried finding adult burrows to dig them out, but the rain had obliterated any trace of the diggings, making their burrows impossible to find. We did, however, note an abundance of larval burrows. I went back to the spot today hoping to see some activity, but thick clouds and cool temps made that unlikely. This is when I decided to “go fishing.” Tiger beetle larval burrows are easily recognized by their perfect circular shape and clean “beveling” around the entrance (1st photo). Burrows of 3rd instars (the last larval instar in tiger beetles) are distinctly larger than those of 2nd instars (2nd photo), while those of 1st instars are smaller still (not shown). Larvae sit at the burrow entrance and ambush any suitable prey that comes too close. During cool, cloudy weather, however, they drop to the bottom of their burrow – up to a foot or more deep. A technique useful for extracting inactive larvae from their burrows is called fishing and involves inserting a thin grass stem down to the bottom of the burrow in an attempt to coax the larva into “taking the bait” and biting the end of the grass stem (3rd photo). The grass stem is then pulled up rapidly – much like setting the hook when fishing – in an attempt to pull the larva out of its burrow before it has a chance to let go of the stem. It can take a few tries, but with practice one can more often than not succeed at removing the grotesquely odd, yet beautiful larva (4th photo). Note the huge, heavily sclerotized head with upward facing jaws. The hump in the middle of the back is armed with forward-curved spines that helps the larva avoid being pulled out of the burrow by struggling prey (but they’re not so effective against obsessive cicindelophiles!). As I managed to “fish” larvae I placed them in a plastic container with their native soil. In the 5th photo, four larvae have already begun digging new burrows, and one more 3rd instar (L) along with a 2nd instar (R) has just been placed in the container. I’ll bring this container back with me and continue to feed the larvae live insects in the hopes of rearing them to adulthood. I cannot say with certainty that the larvae I collected represent C. lengi – other species that could potentially occur at this site include C. scutellaris (festive tiger beetle) and C. limbata (sandy tiger beetle). However, the locality is known for the abundant occurrence there of C. lengi, so I’m hopeful that that is what I’ve collected – we’ll know in a few weeks. In the meantime, I’ll have additional opportunities to look for this species, along with C. limbata, as I pass through the Sand Hills region later this week.

Tomorrow morning I head to the Black Hills in South Dakota, where I hope to find not only Cicindela longilabris laurentii (Boreal long-lipped tiger beetle) in the high pine forests, but also intergrades between this species and the closely related C. nebraskana in the more open habitats of the middle latitudes. Look for an update in a couple days or so.