Oak trees are favorites of the cankerworm.
Cankerworms, commonly known as inchworms, can cause significant damage to fruit, shade and ornamental trees. Inchworms are not a kind of insect, but a group of caterpillars defined by their method of locomotion. This group includes the spring cankerworm (Paleacrita vernata), fall cankerworm (Alsophila pometaria), elm spanworm (Ennomos subsignaria) and the linden looper (Erannis tiliaria). The most commonly attacked trees include apple, ash, basswood, beech, elm, hickory, linden, maple and oak. Fortunately, all types of inchworms can be eliminated using the same method. Does this Spark an idea?
Mechanical Control
Band trees with commercially available sticky traps designed to catch female cankerworm moths. Place traps according to package directions. The female becomes entangled as she climbs the tree seeking a mate.The female cankerworm moth is flightless, so the band can eliminate the breeding population entirely over a period of time.
Biological Control
In the window of time between the hatching of cankerworm eggs and when they reach 1 inch in length, Bacillus thuringiensis (Bt) is an effective control method applied using a pressurized sprayer. For continual control, egg parasites are effective. Egg parasite Telenomus alsophilae and the wasps Trichogramma minutum and Euplectrus mellipes consume eggs of the cankerworm. Hang cards containing egg parasite eggs near where infestations have been seen. Repeat every seven to 10 days until infestations begin to subside.
Horticultural Oil
A 2 to 3 percent dormant oil is effective against spring cankerworm eggs. Apply it to eggs before they hatch using a horticultural sprayer, being especially careful if the trees are active. A thorough drenching is necessary to eliminate all eggs, as some could be wedged in small crevasses.
Insecticide
Several insecticides can be used against cankerworms, but they also destroy any natural predators. Insecticides are considered a treatment of last resort since a decrease in natural predation can have long-term effects on cankerworm populations. Apply insecticide once all the eggs have hatched and cankerworms are visible. Broad-spectrum insecticides such as carbaryl and spinosad are both effective and readily available.
Tags: cankerworm eggs, female cankerworm, spring cankerworm
