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Where Did They All Go?
By Susan Butterfass
Just a little while ago, we were all swatting mosquitoes and flies, worrying about ticks, admiring butterflies, and catching fireflies (and, I hope, releasing them). As the weather cools and the leaves change colors and die, outdoor insects begin to vanish from our perception. Where do they all go?
Ask a kid this question, and you get a simple answer - they all died. Then how come they're back next summer? The usual answer is a shrug.
The real answer to the question is a little more complicated than the kid's answer. Yes, most of them die, but some do not. Because they have many different forms in life and undergo what is called metamorphosis (literally, transformation), there are many different possible ways they can survive the challenges of winter.
Some survive as adults. Asiatic Ladybugs, for example, find nice sheltered places such as our homes in which to escape harsh winter conditions. Certain butterflies, such as the Mourning Cloak, find a snug crevice under some bark and hibernate. Others, such as the Monarch, migrate 3,000 miles or so for a summery Mexican vacation (and their offspring have to find their way back up here without a road map). Honey Bees mass together to conserve heat, with the queen in the middle of the bee ball; individuals are constantly moving from the outside to the inside to take turns being warmer. Other bees and wasps die off, except for the queen, who hibernates underground and creates a whole new colony when it warms up again.
The ones that die have lots of strategies for ensuring that there will be more of them to bedazzle and bedevil us next summer. Some lay eggs that hatch in the fall and then survive as larvae, but they do it in different ways. Firefly larvae, for example, dig down under the leaf mold and hibernate there. Dragonfly and mayfly eggs are laid in and hatch under the water, and the larvae (also known as nymphs) stay underwater waiting for warmer weather before they turn into adults.
Some insects create galls, the best-known ones being on oaks and goldenrod. A gall wasp or fly lays an egg on a specific kind of leaf or stem. The egg then hatches, and the plant part swells as a reaction to the physical actions or chemical secretions of the larva. The larva winds up inside a cozy, edible shelter where it is (relatively) safe from predators and weather. When freezing weather comes, the larva makes some antifreeze to protect the water inside its cells, and the rest of it freezes until warmer weather, when it quickly thaws, becomes an adult, and flies away.
If you know where to look, you might find a chrysalis or cocoon. This is the pupal stage of a butterfly or moth, and although it looks like it's dead, there's a lot of activity going on in there at a rather slow pace: the animal is changing from a wiggly caterpillar to a winged adult. The adult butterfly emerges from its chrysalis when its food supply becomes available - usually nectar, so flowers need to be present. Adult moths, on the other hand, often do not eat, so they emerge, mate, and lay eggs which quickly hatch into caterpillars which eat the new leaves.
You might also be lucky enough to find an egg mass. These have hard, or sometimes fuzzy, outer layers, are wellcamouflaged, and are wonderful protection against cold, wet, wind, and predators. Insects as diverse as Praying Mantids, Gypsy Moths, and Tent Caterpillars die in the fall, but leave egg masses behind to hatch when their food is plentiful.
As you can thus see, most of them didn't go anywhere - they're all still here, waiting for us to discover them if we take the time.
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