Of Beetles

Of Beetles
Conrad Vispo

 

When I was a boy, my father would point out various cars as we drove around – Ford Mustang, Chevy Impala, and VW Beetle. This practice kept me occupied and helped me mark the changes in the World. I still remember our initial sighting of the first-edition Oldsmobile Toronado, a boat of a car that looked like it could house a King Bed. Subsequently, there came the unbelievably small subcompacts of the oil embargo era and, later, the mini-van generation. Car identifying is a habit I’ve tried to maintain despite the flowering of car names and homogenization of styles.

And it’s a habit that I follow in the woods. I don’t search for Hondas or Fords in the brush. Instead, I try to name the trees, the birds, the beetles. It’s a pursuit with some of the same rewards as car-spotting. Take the beetles, for instance. There is a group of beetles known as ‘Ground Beetles’. In New York, there are over 500 species of these beetles. Most resemble the form seen scuttering away from beneath over-turned stones: blackish and relatively elongated (almost Tic-Tac shaped) with long legs for running.

As with car watching, beetle watching brings the fun of hunting natural (or human) invention. Just as I recall that first Toronado, this year I was happy to find a bristly Loricera pilicornis (sorry, that’s its only name). The front end of this beetle is adorned with long, whisker-like bristles that help it collect the miniscule, jumping critters that it eats. Likewise, I can recall my first Sphaeroderus – the Ground Beetle whose head resembles needle nose pliers, a tool it reportedly employs to eat snails.

Another reason that beetle-snooping is intriguing is because it tells you where you are. Just as my mental field notes recorded that the German taxi fleet is composed of Mercedes Benzes and the  Bolivian automobile fauna is dominated by Toyotas, I am, with much help, beginning to discern at the patterns of beetle life, at least locally.

For example, there are the pop-eyed Tiger Beetles who stalk sandy beaches with much the same stop-and-go darting of the Robin. Or, flip a rock along a creek, and one might find a slim and trim Brachinus, bearing its distinctive red head and shoulders and packing a scorching chemical wallop. Go further into the woods, and you encounter a lurching, 1 ½” long Calosoma that has some of the awkward giganticism of a Hummer.

Studying which organisms occur where is not just a matter of fulfilling personal curiosity. It can provide telling insight about the land; about where it has been and where it is going. For instance, two years ago we found 63 species of Ground Beetles in our study of semi-intact floodplain forest in the County. No single species dominated, and the vast majority of the beetles were native.  This past summer, we collected beetles in the vegetable gardens at Hawthorne Valley Farm. A century or more back, these gardens were probably floodplain forest and home to those floodplain forest beetles. Now, one species accounts for more than half of the beetles caught. It is a penny-long, fuzzy, bulldog of a Ground Beetle introduced from Europe. It should not be surprising that such introduced species are at home in the garden; after all, most of our crops originated overseas, as did the Honey Bees that help pollinate them, some of the butterflies who flit through them, certain of the birds who peck at them, and many of the earthworms who work the soil.

The point here is not to judge whether or not such introductions are inherently good or bad. However, one of our responsibilities as conservationists is to maintain our region’s contributions to the ark of the World. Thus the differences between crop field and forest lead to questions like, ‘is there still enough intact floodplain forest to support the native beetles?’ and ‘are there any native beetles for whom the farmlands are preferred stomping grounds?

Naming cars doesn’t, in and of itself, entail many moral quandaries. However, if one has followed the composition of the US motor fleet over the past decades, then one has seen profound changes. Again, “better” or “worse” may not be the proper poles for describing such change, but few economists would argue that ignorance of these changes will help us chart the future of our economy. Ground Beetles are less conspicuous, but they can bring some of the same wisdom, this time about our land. They are, so to speak, one of our ‘leading ecologic indicators’. What do Ground Beetles and the other creatures tell us about where our corner of the World is headed? What does it mean if certain Ground Beetles do or don’t occur in a forest?  For that matter, why are many of the great, glorious moths that flitted around our county in the 1950s now largely absent? Why do we now see the likes of Fisher and Bobcat, and yet so few bats? If one hopes to understand the future, you could do worse than following the fate of Ground Beetles, or counting cars.

Background

car

photo by Marcin Zieliński, from Wikipedia.org
The Oldsmobile Toronado. Somehow it seemed bigger at the time... perhaps I was smaller.

For some good basic information on Ground Beetles and a lot of pictures, see the Carabidae page at BugGuide.Net. This is a great site for whatever bug questions you might have. Once you register (which is free) you can post pictures of unidentified insects and usually get a reasonable identification within a couple of days.

Beetles are the largest group of insects with some 350,000 named types worldwide, and surely many more awaiting naming. In North America, there are around 30,000 species. A 1928 publication on New York's insects (the most recent attempt to collect information on all the State's insects) listed over 4540 species. Certain groups, such as the Rove Beetles (or, scientifically put, the Staphylinids) still remain largely unexplored. Other groups, such as the Ground Beetles, are better known. As the article states, more than 500 species of Ground Beetle are known from New York. So far, in Columbia County we have identified slightly more than 60 species, with new ones still waiting to be classified. This table lists most of those species and gives some hints about their ecologies; it comes from our report on floodplain forests in the County.

The key work that still provides the backbone for North American Ground Beetle identification is The Ground Beetles of Canada and Alaska by Carl Lindroth (1905-1979), it was published in several volumes during the 1960s. It is however expensive and rather technical. A good practical start for regional Ground Beetle identification is Ground Beetles and Wrinkled Bark Beetles of South Carolina by Janet Ciegler. Given its somewhat more southerly focus, it doesn't cover all of our beetles, but the key to the genera is illustrated, straightforward, and pretty complete for our area. Also useful are Ground Beetles of Connecticut by Krinsky and Oliver and the web page Ground Beetles of Canada by Goulet and Bousquet. Both of the last two sources are mainly useful for their pictures and their lists of regional species; neither is, strictly speaking, an identification manual. I am currently working on a regional, on-line guide to this group, but its current stage is too embarassing (and useless) to make public; stay tuned.

Ground Beetles are united as a family by certain anatomical characteristics, such as position of the antennae and shape of the legs and 'thighs'. As with the famed cichlid fishes and with other insects such as certain families of moths and butterflies, what is fascinating is how evolution has built diversity from a common framework. Ground Beetles mainly eat other invertebrates, although some eat seeds or the like. As one delves into them, one sees more and more of the variation that is associated with their different ways of making a living. I tried to touch on some of the beautiful diversity in this article; here, I will present a bit more information about the examples I mentioned.

Loricera may not look terribly fuzzy on first glance (Image1, Image2, Image3, Image4; sorry, taking photos of small things isn't my strength, so I'm linking this material to the dandy photographs already available at BugGuide.Net or to images elsewhere on the net, please just click on "Image1", "Image2" etc). But, if you've spent a little time studying Ground Beetles under a microscope, those coarse bristles will jump out at you. Apparently, these whiskers work as a trap, catching fleeing Collembola. Collembola are tiny, jumping insects that are most familiar to us as the 'snow fleas' that one sometimes finds looking like animate dust on the snow surface during warm winter days.

Sphaeroderus are reportedly snail eaters. They use their long schnoz (Image1, Image2) to rout out snails from their shells (Image1). They may also eat (and may even prefer) slugs.

Tiger Beetles are the pop stars of the Ground Beetles (some people make Tiger Beetles a taxonomic family of their own; we're including them in the Ground Beetles). There are a couple of good books available on these particular beetles: A Field Guide to Tiger Beetles by Pearson, Knisley, and Kazilek and Northeastern Tiger Beetles by Leonard and Bell. One of the reasons that these beetles are, relatively speaking, so popular is because some of them have a striking coloration - the 12-Spotted Ground Beetle (below) for example is common and elegant. Add to this the fact that these beetles are active during the day and favor open areas (beaches, mud flats), and you have the ingredients for high visibility. The stop-and-go hunting behavior of these creatures may reflect some of the same tactics as Robins (these videos, taken by others, show Tiger Beetles hunting: Video1, Video2; compare that to a Robin, Video3). If you are hunting for moving prey (be that an ant, in the case of the Ground Beetle, or a worm, in the case of the Robin), it's probably harder to detect that movement while you yourself are moving. Thus, both animals pause periodically and hold themselves still so as to optimize their ability to sense moving prey. Indeed, your best way of spotting a Ground Beetle is to use the same approach - during summer, find an open flat along a relatively pristine stream and then just stop and stare. Unfocus your eyes so that you are more sensitive to motion and less distracted by detail. If you're lucky, a little darting beetle will catch your attention, and you will have found a Tiger Beetle.

Tiger Beetle

Bombardier BeetleBombardier Beetle Stamp

Brachinus (above) is one of the few other Tiger Beetles that has a common name; heck it even was featured on a US stamp. The common name, Bombardier Beetle, comes from its powerful chemical weapon. Not only have these beetles developed a way of storing these liquids safely (apparently by keeping the relatively innocuous reagents separate until 'firing'), but the nozzle on their rear is able to swivel and aim at desired targets (Video1 see also these still photos of the spray in action). As the video suggests, this seems to be mainly or entirely a form of self defense. The spray can stain one's fingers, and Claudia, who had the misfortune to enhale a bit of it, did not relish the experience.

Calosoma are large, predatory Ground Beetles that come in a variety of hues (Image1). We found relatively few of them during our floodplain forest work, perhaps in part because they may spend much of their time up in trees foraging for caterpillars. The eight or so species of Calosoma which occur in our area are all reported to be caterpillar predators and so, in an agricultural context, are described as beneficials. Indeed, some people call them 'caterpillar hunters', and Susan Mahr of the University of Wisconsin estimates that during the 2-4 year adult life span, a Calosoma may eat "several hundred" caterpillars. One species was brought into the United States as a biocontrol agent for Gypsy Moths in the early 1900s.

Not only are Calosoma adults active predators but their larvae are also voracious. And that brings us to an aspect of Ground Beetle life that I didn't bring up in the newspaper article for want of space - the life of the kids. Ground Beetle larvae look something like sinister caterpillars (Image1, Image2). Most are equipped with large jaws and are predators. Although one occasionally finds them free-roaming in/on the soil, some lead a more organized existence. The larvae of our Tiger Beetles live mainly along stream banks. Wading along the RoJan a couple of years ago, I was surprised by a larval 'colony' - a collection of larvae that had made individual holes into the bank. They stoppered the openings of those holes with their heads, apparently waiting to grasp unsuspecting ants or other insects that happened to tread upon them. The heads were well camoflagued and noticeably less conspicuous than the open burrow holes. However, my presence would cause some larvae to retreat into their burrows, and the effect was the sudden appearance of a hole where, I could have sworn, there was none before. It took me a while to believe my eyes and figure out what was going on.

burrow1

burrow2

Well, there's more to say about Ground Beetles but mainly there's more to learn. Which species do live here (we've already found some surprises)? What do they tell us about the land and its history? As one last, intriguing tid-bit, the following: within some species of Ground Beetles, there are individuals with full wings who can fly and others with less developed wings who can't. Researchers have found that populations in old forests, where there has been little disturbance, tend to be flightless. Populations in forests that have experienced more disturbance tend to have more individuals with full wings, presumably they have been selected for by the need to deal with a more rapidly changing environment. The result is that you can age a forest by the wings of its beetles!

We're still going through the beetles that we collected this past year and hope to do more collections/observations next year. If any of you would like to help, please let us know - we welcome eager volunteers.