Imagine a day in late autumn. The landscape is painted in a palette of grays and browns. You’ve watched the geese fly south. You know that bears, bats, and woodchucks will soon hibernate.
But where are the insects? Sometimes it seems they disappear with the first chill wind. But insects don’t just disappear. They prepare for winter through the fall, and some through the summer, too, just as other animals do.
Maybe because they are so small, or maybe because we are so relieved that they’ll soon be gone, insects’ preparations for winter usually escape our notice.
Monarch butterflies may be one exception. Monarch butterflies are the insect world’s best-known migrants. Their 3,000-mile migration to the Transvolcanic Mountains of Mexico is an epic journey. (Just think what you could do with their frequent-flier miles.)
The Monarch butterflies that flit about in late summer and autumn make the journey from here to Mexico, spend the winter, and in the spring make the first leg of the journey back north. Upon reaching Texas, however, these adults lay eggs and die, leaving the rest of the return trip to subsequent generations. The trip is still considered a true migration because it’s a ‘round-trip that all monarchs take part in.
But monarchs are not the only butterflies that travel to escape the cold. The painted lady migration is not as dramatic as the monarch migration, because it does not occur every year and not all painted ladies migrate. Botanists believe that cyclical variations in climate, such as El Nino, may be related to the butterflies’ cyclical urge to head south for the winter.
Green darner dragonflies do something similar. Most dragonflies, even most green darners, spend the winter as nymphs (an immature life phase) underwater. But some adult green darner dragonflies head south when strong winds blow from the north. Because it’s not organized like the Monarch’s and not all individuals take part, the green darner exodus not considered a true migration.
Mourning cloak butterflies stay close to home, overwintering as adults in the cracks of bark on trees. That’s why you may see a mourning cloak butterfly flitting over spring’s muddy roads, long before any other butterflies are around. They aren’t part of a new generation – they’re the remainder of last year’s.
Viceroy butterflies, those famous mimicking butterflies that look just like monarchs, don’t migrate but rather spend the winter here as caterpillars. In the fall, these caterpillars find a good willow or poplar leaf. The tiny caterpillar rolls itself up in the leaf, binding it to a twig with a strand of silk.
Despite these exceptions, most butterflies – and in fact most insects – spend the winter as eggs. A new year’s bugs generally hatch from eggs laid by adult insects the previous summer or autumn. In general, it’s a far simpler task for eggs to survive the freezings and thawings of winter then it is for fully formed adults.
But it’s the adults that provide the more interesting story. Take the honeybee, the long-term planner of the insect world. Honeybees lay in extra supplies of honey all summer to be used for survival over the winter. The colony stays together in the hive over the winter, with individual bees dining on the stored honey and using that energy to keep warm by shivering.
Our native bumblebees (honeybees are an introduced species) and paper wasps use another tactic to get through our hard winters. In these species, only the queen over-winters. Bumblebee queens spend the winter underground, and paper wasp queens under bits of cracked bark (or in your attic).
Come spring, they emerge, build nests, and lay eggs of sterile workers. In late summer, they lay eggs that turn into fertile males (the first males of the year) and fertile females, who mate and continue the cycle.
These males are members of the “short, happy lives” club, not uncommon in the insect world. They live a few weeks, at most. Their mates are interested in only one thing from them, and it’s not mowing the lawn.
Ladybugs, which are beetles, and cluster flies are two more insects that overwinter as adults. These two get our attention because they often try to overwinter in our houses, substituting the chinks in our wooden shelters for the bark cracks they would have used back in their natural surroundings. (Both cluster flies and house-dwelling ladybugs are not native to New Hampshire and Vermont.)
As you look around the gray and brown landscape, the insects aren’t really gone. Sure, some have flown south. But there are insect eggs and pupae on twigs, under bark, and under the ground. Larvae are wrapped in leaves or safe underwater. Adults are hidden in sheltered places – under bark, underground, and even in our houses – waiting for spring.