Ellen Rathbone: Tracking Adirondack Insects
by Ellen Rathbone
As many of you have probably figured out by now, two of my passions are tracking and books. A few weeks ago a fellow blogger, who is also a field guide fanatic, wrote to me about a new field guide that is just hitting the market: Tracks and Sign of Insects and Other Invertebrates, by Charley Eiseman and Noah Charney. Well, what right-minded tracking bibliophile could pass up such a title? I had to order it. The book is so freshly off the presses that there was a small delay in shipping, but this morning it arrived.
Now I know what you are thinking. She’s gotta’ be nuts if she thinks she’s going to follow beetle footprints! And you’d be right – that would be nuts, at least here in the woods it would be nuts. But tracking isn’t strictly looking for the proverbial footprints in the sand. A “track” is a footprint, but “tracking” involves looking for all the other “signs” animals leave behind: droppings, eggs, nests, dens, feeding sites, shed fur/skin/feathers, etc. So, in the case of insects, one can certainly look for footprints (especially if sand is around), but one should also look for insect cases, holes in trees, chewed leaves, cocoons, nests, and so on. It is for these clues that I bought the book.
Many’s the time I’ve gone out with students and while pulling apart the trunk of a rotting tree encountered various and sundry signs of insects. They might be tunnels, they might eggs, they might be cocoons or webbing. Invariably, one of the students asks “what’s that?” Most are satisfied with “that’s a cocoon,” or “those are insect eggs,” but the curious naturalist in me wants to know more. Whose cocoon? Whose eggs? I’m hoping this book will provide the answers. Just flipping through the pages, it looks pretty darn promising, for it is chocked full of good quality photographs and plenty of descriptive text.
In the opening remarks the authors mention looking for the signs of “slug teeth.” Slug teeth? Slugs and snails don’t have proper teeth like you or I; they have an apparatus called a radula, which is a rasping mouthpart used to scrape thin layers off their food of choice. Last summer I found a large snail in the garden and commenced trying to capture its portrait with a camera. I held it on a leaf in my hand and it slowly oozed around, investigating this new environment. When it reached the edge of its leaf and found itself facing my naked hand, the first thing it did was try to sample me with its radula. For someone notoriously squeamish about invertebrates on bare hands (they have strange feet and might bite), you can imagine this was a startling sensation. Luckily for the snail, I didn’t fling it from my hand. I did shake it, though, enough to discourage its continued sampling. But I digress. The point is that on the right surfaces (not my hand), one can actually see the marks made by a slug or snail’s radula as it scrapes together a meal. How cool is that?
How about leaf mines? These are the tunnel-like lines you find wandering around on a leaf, like someone has turned it into a foliar etch-a-sketch pad. These tunnels, for that is indeed what they are, are made by larvae that live between the epidermal layers of the leaf. That’s a pretty small space, so one can only imagine just how small the larvae must be. If one investigates the marks closely, one will likely see that one end of the tunnel is narrower than the other, for the larva grows as it tunnels/feeds. Eventually, unless it is eaten or parasitized by some other critter, the larva pupates and emerges as an adult – look for the appropriate exit hole. If you are really lucky, you might even find the cocoon still nestled in the leaf before the adult hatches. With this field guide, you have a fair chance of learning to identify which leaf mining insect it is.
There’s even a section on galls! This is very exciting, because galls are one of nature’s treasures. I’ve written about some of the galls I’ve found, but finding information on galls hasn’t always been easy. Thank goodness for the internet, which can be a field guide in and of itself, provided you know what you are looking for and that you use reliable sources. But now I have a field guide in hand that has almost 30 pages just about galls! Can life get any better?
A whole new world of possibilities is now laid out before me. I can hardly wait for my next adventure outside. Pretty soon I’ll have to hire a Sherpa just to carry all my field guides every time I head out into the woods, but it will be worth it so I can learn a bit more about the critters that call the Adirondacks home.



















