Entfact 806

C. Ware 1998

Winter Hideaways

By Lana Unger,
Extension Entomology Specialist

Have you ever wondered where all the insects go during the cold winter months. They seem to have all disappeared. You don't hear the crickets chirping or see butterflies flitting about. But they are not very far away. In fact, they are probably right under your nose ... if you know the right places to look.

Unlike humans, insects are cold-blooded. Their body temperatures rise and fall with the air temperature around them. Some adult insects such as certain butterflies and grasshoppers cannot take the cold and die off in the winter. Although the adults die, other life stages, such as eggs, larvae and pupae are able to survive the cold by entering diapause, a period of little or no activity.

Galls

M. Johnson 1981

Some insects survive the winter by creating galls on plants. A gall is made up of extra thick layers of plant tissue that grow around an insect. Usually an adult insect lays an egg on the plant's surface.

The young larva that hatches from the egg, bores into the plant tissue where it becomes surrounded by the gall. Once the gall has formed, the insect stays happily inside the gall, pupates, and emerges in the spring when the weather is nice. There are more than 1500 gall-forming insects in North America. Most gall-forming insects are wasps, flies, beetles and moths.

Body heat

Underwater

Other aquatic insects, such as dragonflies and damselflies spend the winter underwater as naiads, the immature life stage between egg and adult.

Ice-covered ponds can be homes for water boatmen and backswimmers. They stay in air pockets under the ice.

Underground

Migration

Corel PhotoCD

Some insects take an extended vacation when the weather turns cold. One of the most well known migrating insects is the monarch butterfly.

ACTIVITY

Gall-y Gee Whiz

Things you will need:

• scissors
• knife
• jars
• cheesecloth or fine screen
• rubber bands

Goldenrod plants often have round or egg-shaped galls on their stems. During the winter, the plants will be dead, but the insects within the galls are still alive. You might also be able to find galls on oak trees.

Use scissors to cut the stem or branch below the gall. Collect as many galls as you can find. Ask an adult to help you open some of the galls with a sharp knife. But be careful not to cut the larva inside. If the gall is empty, the gall may be old and the insect may have already emerged. Look for exit holes on the gall. Also birds or other predators may have killed the gall-forming insect. You may be surprised to find a spider or beetle inside the gall taking advantage of the protection from the cold.

Place the rest of the galls in jars. If the plant was still alive when you cut your sample (trees for example), place the cut end of the branch in a cup with a little water so that the branch does not dry out. Place the cup and gall inside the jar. If the plant was already dead (goldenrod), you will not need to provide any additional water. Cover the jars with fine screen or cheesecloth and secure them with rubber bands.

Everyday, check your galls to see if the insects inside have emerged. You may see small wasps, flies, beetles or moths that originally created the gall or you may see a parasitic wasp that killed the original insect and took advantage of the gall's protection.

Keep a journal about your galls:

• Record what types of insects emerge from different types of galls.

• Compare the size of the gall with the size of the insect that emerges.

• How long does it take for the insects to emerge?