Dormancy and boxelder bugs

When deciduous plants become dormant, look for boxelder bugs to become active

Dormancy in plants

Most broad leaf (deciduous) plants enter a period of dormancy after they drop their leaves. Becoming dormant is a defense mechanism for survival during cold or very dry weather. Dormancy is triggered by the amount of daylight vs. dark (photoperiod), temperatures and lack of rain.

During the summer, trees have well-developed leaves that trap sunlight, converting it to sugars that help the plant grow. Sometime during September, changes occur in the plant that trigger two things -- the formation of an abscission layer in leaves and the movement of sugars from the upper part of the plant down to the roots. These changes cause the fall colors in leaves. Eventually, the leaves drop, the sugars are converted to starch and winter buds develop where leaves once were.

This process reverses itself in the spring when environmental conditions cause the "sap to rise" and leaves to unfurl.

Evergreens never go into true dormancy. They normally have small "needles" or waxy coverings on their leaves that prevent drying out if the soil becomes frozen and the plant can not take up water.

The boxelder bug (Boisea trivittata) is mostly known as a nuisance because they sometimes invade homes during the fall. These insects can congregate by the thousands on sunny walls; if the home is not well insulated, the insect can make its way inside in large numbers.

Boxelder beetles overwinter as adults and lay their eggs on box elder and silver maple trees. The young nymphs hatch in a few weeks and grow over the summer. They are typically attracted to female boxelder trees, those that bear the winged samara-like seed. They feed on the leaves, flowers and seed pods of the host tree, doing very little damage to the trees.

The adults begin to seek out warmer locations, such as houses, in fall. The best way to keep them from invading your home is to remove female box elders from landscape settings and to seal up holes around windows or doors. You can spray the bugs if they are congregating on the side of your house. A mixture of dishwashing soap and water is usually adequate to stop these insects.

Nature Notes for 11/04/2022