Control winter moths now

Winter moth (Operophtera

brumata) originated in Europe and came to B.C. in the 1970s. The larvae — smooth, green inchworms about 1/4 long — hatch in spring and can cause serious damage to emerging leaves if not controlled. After three years of infestation, the tree can become so weakened that dieback and possible mortality can occur.

Favourite hosts include oak, apple, crabapple, ash, birch, maple and other broadleaf trees. Damage from winter moth has been extensive this year, with blueberries and roses also falling prey to their voracious appetites.

The following excerpt from Linda Gilkeson’s website explains effective means of control. The time is right now to get this done.

Tree Bands: If winter moth caterpillars ate holes in your tree leaves early last spring (apples and other fruit, oaks, deciduous trees), then mid-October is good timing to put up sticky tree bands to intercept the females before they lay eggs. Female moths can’t fly, so when they emerge from their cocoons at the base of trees, they have to walk up the trunk to lay eggs on the branches. Spread insect glues like Tanglefoot, Tangletrap and Tree Guard Tape on a foot-wide band around tree trunks.

The band can be anything that is easy to wrap around the trunk: plastic food wrap or other waterproof material that can be spread with glue. If the tree has deep crevices in the bark, wrap a layer of cotton batting around the tree first, pushing it into the cracks to block moths from crawling under the sticky band. Don’t put the glue directly on bark. It will damage young bark and also keep on catching insects, mainly beneficial ones, during the growing season. The moths lay eggs from late October to January so you can remove the tree bands in February.

More extensive details on Winter Moth are in Linda’s book, “Natural Insect, Weed and Disease Control”. She mentions removing and replacing the bands when they become full of trapped moths, and making sure each trunk of a multi-trunked tree is banded. On a lighter note, she advises placing the bands high enough to avoid small children’s hair or dog’s tails. Further options mentioned are:

• Spray dormant oil between December and February; this smothers the eggs. This must be done before buds begin to swell.

• Spray BTK (Bacillus thuringiensis

kurstaki) in the spring when caterpillars are small and actively feeding. Make sure to get the spray into new buds and rolled leaves.

• More of a prevention than a cure, plant to attract beneficial insects, beetles, ants and birds, which will eat the cocoons left on the ground. We thank Linda Gilkeson, PhD entomologist for her help and advice regarding these pesky varmints. Russell Nursery, 1370 Wain Rd., N. Saanich russellnursery.com