St. Anthony Dune Tiger Beetle

Sand dune habitat for Cicindela arenicola | vic. Idaho Falls, Idaho

After kicking off the 2011 fall tiger beetle trip by finding Cicindela formosa gibsoni and C. scutellaris yampae in the Yampa Valley sand dunes in northwestern Colorado, I was even more optimistic about my chances of seeing the main goals of the trip—the four C. maritima species group endemics that inhabit sand dunes in Idaho (St. Anthony Dune Tiger Beetle—C. arenicola, and Bruneau Dune Tiger Beetle—C. waynei), Utah (Coral Pink Sand Dune Tiger Beetle—C. albissima), and Colorado (Colorado Dune Tiger Beetle—C. theatina).  Each of these closely related species is restricted to a single sand dune system in their respective states, resulting in small populations that are especially vulnerable to drought and threats to their required habitats (primarily invasive plants and offroad recreational vehicles).  Cicindela arenicola, described from the St. Anthony Dune system of southeastern Idaho (Rumpp 1967) was our first target, and while the drive through the Snake River Valley—aspen and maple in blazing full color—was stunningly beautiful, all I could think about during the 6-hour drive was the rising temperatures outside and the tendency of these sand dune tiger beetles to dig in if it gets too hot.  I had information about several localities along the St. Anthony Dune system, and by the time we arrived at the first of these it was already early afternoon.

Cicindela arenicola adult burrows

Walking onto the dunes at a locality near Idaho Falls, it didn’t take long to find the unmistakable signature of adult activity—burrows.  Many insects (especially bees) and even non-insects (spiders, solifugids, etc.) that live on sand dunes create burrows that can look similar to those created by adult tiger beetles.  However, after years of experience I can almost tell at a glance whether a burrow has been created by a tiger beetle versus some other arthropod by the size and shape of the opening and appearance of the diggings.  When there is doubt, a little bit of excavating with a knife gives further clues in the shape of the tunnel—flatter than most other diggers and angling almost horizontally back into the sand before taking a dive a few inches back.  Wind quickly obliterates evidence of the burrow entrance and pile of diggings, so when these are present and fresh-looking the beetles have either just dug in or just dug out.  I excavated a number of burrows that turned out to be empty, suggesting the beetles were out and about if only I could find them.  And find them I did, mostly along the sloping, south-facing dune face above the flatter sand plain below.  They were as beautiful as I imagined they would be—bold, white markings, screaming green and copper highlights on the head and pronotum, and a dense covering of white hairs on the sides and undersurface.  They were also extremely active and wary, so much so that I didn’t even attempt to photograph them for the time being despite the decent number of individuals that we saw at the site.

Cicindela arenicola adult excavating burrow (click for better view of beetle just inside burrow entrance)

Cicindela arenicola in completed adult burrow | September 2011 | Idaho Falls, Idaho

There were other nearby sites that I had planned to check also, but with good numbers seen already and several other interesting insects (e.g., Crossidius spp.) found in abundance on the blooms of snakeweed plants growing on the backside of the dunes, there was really no reason to go anywhere else.  Besides, I still had not even attempted a field photograph of C. arenicola (although I had made sure to capture some live adults for studio shots that night as a backup).  As the sun began sinking in the western sky and temperatures began to cool off, I noticed the adults were becoming scarce and that fresh burrows were appearing on the dune surface.  In contrast to earlier in the day, adult beetles were found in nearly every burrow that I excavated—the beetles were digging in, and if I wanted field photographs it was now or never.  I managed a few distant shots of the first several adults I tried to stalk, but none of these were close to keepers.  I eventually noticed that beetles in the sparsely vegetated areas of the dune seemed to be slightly more approachable than those out on the open dune surface (perhaps they felt a little more secure in the presence of some cover), and although the vegetation often obscured clear views of the beetles, it was at least a more manageable problem than not even being able to approach them.  Finally, after considerable effort, I managed the photograph shown below.  I’d like to take credit for the near perfect composition and focus, but it was an actually a completely accidental shot.  I had been stalking the beetle for some time and had finally gotten closer to it than I had managed for any other beetle.  Rather than a presenting me with a lateral profile, the beetle was directly facing me as I closed in for the shot. Just as I pressed the shutter the beetle turned profile and then darted off.  Other than nipping the middle tarsus I don’t think I could’ve framed this uncropped photo better if I had tried.

Cicindela arenicola | September 2011 | vic. Idaho Falls, Idaho

Cicindela arenicola is closely related to C. waynei (known only from sand dunes in and around Bruneau Dunes State Park in southwestern Idaho), and it is only recently that the two have been considered separate species.  Cicindela waynei differs in its generally green rather than bronze coloration, more expanded white markings, and the presence of a curious upward projecting tooth on the male mandible (Pearson et al. 2006).  There are some populations in south-central Idaho assigned to C. arenicola that show an intergradation of characters between the two species, primarily in the presence of individuals with green coloration and expanded markings, so I found it interesting to encounter just such an individual at this southeastern Idaho site as well.  The individual, a male (and photographed in a terrarium that evening), looks very much like C. waynei except that it lacks the distinctive mandibular tooth characteristic of that species.

Male from same locality with green elytra and expanded markings

Cicindela arenicola is largely restricted to the Snake River Plain of southern Idaho, with a small population also occurring in the Centennial Sandhills of southwestern Montana (Winton et al. 2010). The sand dunes on which these beetles depend have suffered numerous assaults in recent years at the hands of man, with exotic invasives (Bouffard et al. 2009), trampling by cattle (Bauer 1991), and offroad vehicular traffic having the greatest impact on tiger beetle populations.  The species has been considered for listing on the Endangered Species List due to the imperiled nature of its limited habitat, but to this point such status has not yet been accorded.  It has, however, been listed as globally imperiled by the Idaho Department of Fish and Game and the Bureau of Land Management.  Most people are completely unaware that this beetle exists, and probably fewer still would even care.  For me personally, however, the chance to see this rare and beautiful beetle in its native habitat and spend time watching its behavior was a thrill I won’t soon forget.

Tiger beetle's-eye view of its preferred sand dune habitat.

I haven’t forgotten about the challenges that led to this post.  However, the hour is late and I need my rest.  Points will be awarded over the next day or so, and the winner of BitB Challenge Session #4 will be crowned!  In the meantime, I’ve released the submitted comments so you can see how your answers fared against the competition—no do-overs!

REFERENCES:

Bauer, K. L. 1991. Observations on the developmental biology of Cicindela arenicola Rumpp (Coleoptera: Cicindelidae). Great Basin Naturalist 51:226–235.

Bouffard, S. H., K. V. Tindall and K. Fothergill. 2009. Herbicide treatment to restore St. Anthony tiger beetle habitat: a pilot study. Cicindela 41(1):13–24.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States & Canada: Identification, Natural History, and Distribution of the Cicindelidae. Oxford University Press, New York, NY. 227 pp.

Rumpp, N. L. 1967. A new species of Cicindela from Idaho (Coleoptera: Cicindelidae). Proceedings of the California Academy of Science 35:129–140.

Winton, R. C., M. G. Kippenhan and M. A. Ivie.  2010.  New state record for Cicindela arenicola Rumpp (Coleoptera: Carabidae: Cicindelinae) in southwestern Montana.  The Coleopterists Bulletin 64(1):43–44.

Copyright © Ted C. MacRae 2011

About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
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17 Responses to St. Anthony Dune Tiger Beetle

  1. Welcome back! I’ve been missing your articles showing-up on my reader. The green C. arenicola is stunning…how I envy your ability to still find bugs like this in late October!

    • To be honest, these were taken in late September. Southern Idaho isn’t too terribly far from your area, so I obviously had some good luck with weather considering the lateness of the season. Still, it just boils down to time in the field my friend, time in the field!🙂

  2. Ben Coulter says:

    These are just fantastic. Of the genus Cicindela, the maritima sand dune endemics are probably the ones I covet most. Photos like these are not helping my addiction.

    • Thanks Ben. I had longed to do the western sand dune tour for several years, so it was an easy choice when my plans for Texas changed at the last minute.

      I so totally lucked out with that field shot!

  3. hemachatus says:

    Amazing photos of some really cool bugs!

  4. Ani says:

    Ted, I had seen a C. lepida digging a burrow in the sandy region of southwestern Ontario, but when I googled for this behaviour I did not find any references. Thanks to your wonderful article, I now know that s/he was indeed digging a burrow to root in the night! I like all the images here and the Beetle’s POV is my favorite!🙂

    • Yes, I too am a little surprised at how little the adult digging behaviors have been documented and discussed, both online and in some of the field guides. In fact, some species not only dig in for the night but also during the day if it gets too hot – I’ve seen lepida and scutellaris do this, completely disappearing by early afternoon. I’ve done just about as much collecting of many of the dry sand inhabitants by digging them out of their burrows as I have netting active individuals.

      I really like that POV shot myself!

      • Will Richardson says:

        Last week, I witnessed dozens of C. oregona digging burrows at a playground somewhat distant (a few hundred meters inland) from their typical beach habitat here at Lake Tahoe. This was in the middle of a warm day, but definitely not too hot (hundreds were active on the adjacent parking lot), so I have to wonder if they were prepping to overwinter. We had just had a couple very stormy couple of days, which is perhaps how they all ended up blown inland, but I’m wondering if the weather might have inspired the behavior as well. There is definitely a paucity of information regarding adult burrows out there, at least from what I’ve found so far. All I have is speculation and some fun video of three adults digging burrows side by side. Any lit you could point me to?

  5. James C. Trager says:

    The burrows always seem to be placed in the trough between the sand ripples.
    I learned recently that least terns apparentlly always nest on the upper lee side of dunes.
    Somehow these seem related, and get me to thinking about the speciall behavioral adaptations of locomotion and nesting for life in sand dune.
    Speaking of life in the dunes, did you happen to see any of the bright yellowish Formica bradleyi there?

    • I believe also that the placement of these burrows in the swales is more than just coincidence – perhaps the sand is more stable there and doesn’t collapse so easily when digging is initiated, or less likely to get buried or blown away?

      I tend not to see too many ants (or anything else) when tigers are actiive!🙂

      • James C. Trager says:

        Yeah, I understand. Believe it or not, I miss the larger and more conspicuous tigers when consumed by ant activity.

  6. Scott says:

    Great photos in the post and as always excellent writing. That tiger beetle sure is a looker fantastic capture.

  7. TGIQ says:

    Ted, your beetle portraits are getting scarily good….

  8. Pingback: Cicindela albissima—The Coral Pink Sand Dunes Tiger Beetle « Beetles In The Bush

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