Where Are the Insects?

Few insects have been reported over the past several weeks — it’s cold outside! But, even with the colder weather there are still insects among us. If you look hard enough you can find a few crickets under the grass alongside the path on the Explore the Wild/Catch the Wind Loop, perhaps a grasshopper, or a few beetles. But there’s more than just a few crickets, a grasshopper and a beetle or two around. Consider all the dragonflies, beetles, grasshoppers, butterflies and moths, and other six-legged creatures that were seen during the summer and fall months at the Museum. Of those that weren’t eaten by birds or other insects, many have no doubt reproduced. Some may overwinter as eggs, larvae, or pupae in the soil, in tree trunks, or in the leaf litter beneath the trees.

As you walk around the Explore the Wild/Catch the Wind Loop, the larvae of the Metallic Woodboring Beetles (see Insects, Explore the Wild Journal, July 1-15, 2008) that were seen this past summer are most likely munching away on the wood beneath the bark of the trees that you pass on your stroll. If you see a woodpecker pounding away at a tree trunk, stop briefly to listen, and then start pounding again, it’s probably after a grub inside the tree.

gd_12_1dowoMany of the butterfly and moth species seen during the past summer and fall months spend the winter as either eggs, pupae or, in some cases, as adults in the crevices and cracks of trees, or under the bark. You may see a Questionmark (a species of butterfly that overwinters as an adult) flying about on a warm winter’s day. Certain moth caterpillars wrap themselves in leaves and spin cocoons in preparation for the following spring’s emergence. The image at left shows one such silkmoth cocoon hanging from a vine, a Downy Woodpecker trying desperately to make its way through the surprisingly tough exterior of the moth’s winter retreat.

As evidenced above, the activities of birds often provide proof of the presence of insects. Over the past two weeks I’ve seen Eastern Phoebes flycatching in both Catch the Wind and Explore the Wild. It’s hard to know exactly what they’re catching but in certain lighting conditions you can see swarms of small flies, perhaps midges, flying about. When not at the bird feeders, Carolina Chickadees, White-breasted Nuthatches, Ruby-crowned Kinglets, Brown Creepers (see Brown Creepers, Explore the Wild Journal, November 16-30, 2008) and many other birds, are constantly foraging among the trees for insects, in one form or another.

gd_12_1dragSince last spring, I’ve seen 27 species of odonata (dragonflies and damselflies – odes) on the Explore the Wild/Catch the Wind Loop. Most, if not all, of those odes have deposited eggs in the water of the Wetlands. The eggs that have survived have hatched into nymphs, or dragonfly larvae (image at left), and are now on the prowl beneath the surface of the Wetlands. Those 27 observed species consisted of many individuals, the females of which have deposited hundreds or even thousands of eggs in the water. That’s a lot of nymphs! They don’t all survive, of course, but the numbers are still impressive.

gd_12_1wabo1Although they can’t easily be seen, many other aquatic insects lurk beneath the surface of the Wetlands. Predaceous Diving Beetles, Water Boatmen, and Backswimmers are still active and swimming below the surface. For those who prefer to experience wildlife and not simply imagine it being there, you need only go to the Sailboat Pond, carefully lean over the wall (don’t fall in, the water’s cold) and peer down into the crystal clear water. It may take a few tries, but you should be able to pick out Water Boatmen clinging to the walls or bottom of the shallow pond and perhaps Backswimmers hanging motionless in the water, or doing the backstroke through the water. I’ve seen quite a few of both in the Sailboat Pond during the first two weeks of December.

Water Boatmen and Backswimmers are interesting creatures. Although they belong to different families of insects (Corixidae and Notonectidae, respectively), they are similar in that they both propel themselves through the water using their rather long hind legs as paddles. There are about 125 species of Water Boatmen and 32 species of Backswimmers in North America. Although Backswimmers on average are larger than Water Boatmen, Water Boatmen are the larger of the two species (about 3/8 inches in length) that have recently been seen in the pond. Water Boatmen swim rightside up and Backswimmers swim upside down, or on their backs.

gd_12_1wabo2Besides their attitude when moving through the water, Water Boatmen and Backswimmers are different in several other respects. The front legs of Water Boatmen are short and flattened at the tips and are used to scoop up algae and decaying plant and animal matter from the bottom in which to eat. The middle legs are much longer and are used to cling to objects in the water to keep them (the insects) from floating to the surface. They breath by trapping air, captured from the surface, under their wings and around their abdomens in the form of an air bubble which makes them rather buoyant, hence the need to cling to something in order to stay submerged. The hind legs are also elongated, but unlike the middle legs, are broadened at the ends with many tiny hair-like filaments making them paddle-like in both appearance and function.

gd_12_1backBackswimmers, as mentioned, swim belly up. The hind legs are elongated and, again, perform the job of propelling the insect through the water. In the photo at left the front and middle legs are folded onto the body and the hind legs are extended out to the sides, ready for action. Their front and middle legs are approximately equal in length and have small spines on them to hold prey while the Backswimmer pierces the prey with its beak-like mouth parts. They seek out other small invertebrates, first piercing their skin with the beak, then sucking out the unfortunate prey’s body fluids. They may even take small fish and tadpoles. Given the Backswimmer’s predatory feeding behavior, one other difference between Water Boatmen and Backswimmers should be noted: unlike Water Boatmen, Backswimmers can give you a painful bite.

gd_12_1wascBackswimmers may, in turn, fall prey to another denison of the Wetlands, a Water Scorpion (image at left). Water Scorpions are long, slim, slow-moving insects which capture their prey much like a mantis, with a quick pounce using their specialized front legs.

So, you see, there’s a lot of insect activity out there on the Explore the Wild/Catch the Wind Loop. Insects may not be buzzing around your head, hopping along down the path, or sipping nectar from flowers alongside the path as in summer, but they’re out there. Glimpses into the lives of insects can still be had, no matter what the season; you just have to be willing to take a closer look at what’s around you.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.