Life Cycle of a Caterpillar 

Cankerworms are caterpillars that feed primarily on the leaves of American elms, Manitoba maple and Green ash in May and June. Cankerworms spin down from trees on silken webs. In Winnipeg, we have a spring and fall cankerworm. Both the spring and fall cankerworm are about 2.5 cm long when fully grown. They range in color from light green to brownish green with a dark stripe down the back.

The fall cankerworm adult, which is a moth, lays its eggs in the crown of the tree before winter. It usually does this after the first severe autumn frost. The spring cankerworm adult, also a moth, lays its eggs on trees in the early spring. It lays its eggs after the first major spring thaw. The fall and spring eggs hatch into cankerworm larvae in the spring.  

Cankerworms can travel on their silken threads as larvae and travel to nearby trees. We would encourage you to speak with your neighbors and join together to band the trees on your block. We are happy to offer special pricing for a bulk order. 

When is the Right Time to Apply the Banding? 

The best way you can control adult cankerworms is to band your trees before the wingless female moth ascends the tree to lay her eggs in the crown of the tree. In Winnipeg, that means that trees must be banded before the first hard frost to control the fall cankerworm and left on until early June to control the spring cankerworm.  

Lawn Care Duo bands trees in September and will return mid-June to remove the banding. Banding needs to be replaced annually to prevent the bark from rotting due to excessive moisture. 

Once the cankerworms are hanging on their silken threads, contact chemical control is the only possible alternative. Whenever you use a pesticide, always follow label directions. This is not a service that Lawn Care Duo provides.