Photos courtesy of
Entomological Society of Saskatchewan
Spring Cankerworm Larva
Fall Cankerworm Larva
Female Cankerworm Moth
Male Cankerworm Moth
Cankerworms are the larvae of 2 types of moths, the spring cankerworm moth and the fall cankerworm moth. Both moths have larvae that appear at relatively the same time in the spring, the difference being the fall moth lays her eggs in the fall, where they remain over winter in tree limbs as eggs and hatch out in the spring, whereas the spring moth emerges from a cocoon in the spring and climbs the tree to lay her eggs, which are hatched a few weeks later.
Though the life cycle of the cankerworm is weather dependent, bands should normally be in place by the end of March. The band should be removed by mid May, allowing the bark underneath them to dry out.
These bands should be reapplied in the fall, around the second or third week in September before the first hard frost to lessen infestations of fall cankerworm moths which emerge from their pupas at that time and crawl up the trees to lay eggs. It is very important that the traps be properly greased and that the traps be checked on a weekly basis until late October to make sure that the grease is free of foreign material to work effectively.
The traps should be regreased in mid March and checked each week until late April to prevent infestation from Spring Cankerworm Moths. The larvae from both the spring and fall cankerworms (the cankerworms themselves) both are born in mid to late May, immediately after the leaves of the elms bud out.
How to band a tree:
All elm, Manitoba maple and fruit trees on or adjacent to your property should be banded.
Wrap a four to six inch wide strip of fibreglass insulation around the trunk - about five feet off the ground. That's out of reach of pets and young children.
Cover the insulation with a sheet of plastic wrap or cling wrap. Allow several inches of plastic above and below the insulation. A black plastic garbage bag will do.
If you are using plastic wrap, tape the plastic to the tree with duct tape. If you are using cling wrap then the duct tape is not required. Do not use nails or staples.
Spread a layer of a sticky substance, such as TanglefootTM or axle grease or petroleum jelly, on the plastic.
Inspect the sticky material regularly and remove leaves, insects and other debris and reapply sticky material if required.
Bands should be removed by mid May and reapplied by mid September. Removing the bands prevents damage or discoloration of the bark.
