Background

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.



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.

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.