Identifying the Damage

Apple clearwing damage swollen infested rootstock, Amanda Brown, BC Tree Fruit Production Guide

Amanda Brown, BC Tree Fruit Production Guide

Larvae tunnel under the bark anywhere from below the crown area up to the branches. They enter the trunk through burr knots, wounds, grafts, branch collars, pruning cuts, and wire damaged areas. Infested rootstocks appear swollen. To check for larval infestations, examine the bases of trees for 2-3 mm-wide holes and tunnels under the bark or in burr knots. Pupal cases and/or frass may be evident at the tunnel exits.

The larvae weaken the host tree, reduce the crop yield and make the tree more susceptible to attack by fungal diseases. In the drier Southern Interior of BC, infested trees are also prone to drought stress which can contribute to the death of the trees.