The City of Winnipeg’s Insect Control Branch, along with Trees Winnipeg (formerly Coalition to Save the Elms), strongly recommend that you band your elm, ash, maple and ornamental (basswood, cherry and apple) trees as soon as possible, to prevent the potential defoliation of your trees next spring by cankerworms.
Band your trees in the fall, before the first frost. Bands can remain on the tree over winter. In late winter or by March 15, check your bands, clean and apply additional Tanglefoot® to protect the tree from females which will emerge in the spring. If the band is coated with moths and other debris, the cankerworm moth may crawl over the band; therefore it is important to make sure the band is clean and clear of debris.
Remember to remove bands by May 15. A good rule of thumb is to band the trees in early September and take them off on the May long weekend. Bands that are left on the trees over the summer can cause tree rot, encourage insect infestations and are unsightly.
In the fall and spring of each year adult cankerworm moths emerge from the soil around the drip line of deciduous trees. The female moth is wingless and must crawl up the tree trunk to mate and lay eggs in the upper parts of the tree. Male cankerworm moths have wings and are able to fly to the tree to mate with females. Sticky Tanglefoot® bands capture the females before they are able to climb into the upper portion of the tree to lay eggs.
Spring and fall cankerworm caterpillars hatch from the eggs in the upper part of the tree in spring and eat the leaves. As cankerworm caterpillars grow in the spring, they are able to infest adjacent trees by hanging from silk threads which contact nearby trees. Therefore it is important to band all susceptible trees if they are growing close together. Elm, ash, maple, ornamental (basswood, cherry and apple) trees should be banded.
Trees Winnipeg (Coalition to the Save the Elms), a non-profit charitable organization dedicated to the stewardship of the elm and other trees, forests and the urban environment with the City of Winnipeg’s Insect Control Branch are highly recommending that you band your trees as soon as possible to prevent the potential defoliation of your trees next spring by cankerworms.