Backyard Nature - Where insects go in Winter
I was recently walking through the bush with my family, when my son pointed out something odd-looking. It appeared to be a used-up tea bag that someone had flung into a shrub, where it became stuck to a branch. We took a closer look and realized it was an elongated casing made of a tightly woven, hardened organic material. We had found the cocoon of a Cecropia moth.
This led to the bigger question – just where do insects go in the winter? Cecropia moths are just one of thousands of species of insects, and they all have their own way of dealing with the Canadian winter.
Some simply get out of town. Monarch butterflies are the best-known migrants in our area. Each fall they begin the arduous trip to their over-wintering grounds in the highlands of Mexico. But most local insects stay local and over-winter in a life stage particular to their species. Insects have either a complete or incomplete life cycle. Those with a complete life cycle (butterflies, moths, bees, wasps, ants, beetles, for example) have four life stages: egg; larva, caterpillar, or grub; pupa; and adult. Those insects with an incomplete life cycle (crickets, grasshoppers, bugs, dragonflies, damselflies, for example) have three life stages: egg, nymph, and adult.
A good example of an insect that over-winters in the egg stage is the praying mantis. In the fall, the female lays the eggs in a froth on a stem. The froth then hardens and protects the eggs until they hatch in the summer. In the winter, look for these egg masses, roughly the size, shape and colour of an English walnut shell half, on grass stalks in old fields.
Insect larvae are not too difficult to find in winter. I stopped by a nearby creek and snapped off the top of a cattail plant. I gently pried apart the cigar-shaped seed head, loosening all the feather-light fluffs and revealed a tiny white grub nestled in this protective abode. Always keep an eye out for tumour-like growths on plants: elliptical swellings on the stems of goldenrods, pinecone-like formations at the tips of willow branches, or woody “apples” forming on oak branches. These formations, called galls, are formed in reaction to larvae dwelling inside the host plant.
Have you ever been surprised by the sight of ladybird beetles clustered on the sun-warmed windows of your house in early spring? These insects over-winter in their adult stage, gathering together and hibernating in sheltered areas inside buildings or under fallen leaves and logs outdoors.
Damselflies and most dragonflies spend their winters as nymphs under mud or rotting leaves in the water. Come spring, they crawl up onto land, split open the back of their nymphal skin and emerge with a fabulous set of adult wings.
So remember when you are out walking through a snowy wonderland – you are not alone. You are surrounded by insects. You may not see them, hear them, or feel them, but they are there, nevertheless, just waiting to become active once their surroundings warm up.