What are winter moth caterpillars? Should I wash my tree in Winter?

Winter moth is the name given to several different moths where the females have no wings, they emerge from the soil between November and April and climb up trees and lay their eggs.

Eggs hatch as the trees start to bud and caterpillars emerge and start feeding. The caterpillars continue to feed until early June. They then go down into the soil where they pupate.

This pest problem is mainly found in apple, pear, plum and cherry trees. Winter moth caterpillars eat holes in the leaves, blossom and developing fruit. Extensive damage to fruit trees can affect crop yield and quality.

Feeding damage is most noticeable in the summer when the leaves are fully expanded and the holes made during the spring have enlarged with leaf growth. The caterpillars have left the tree at this point.

Blossom and developing fruit can also be damaged, early damage on apples can cause a deep graze to develop by the time the fruit have reached full size in late summer.

The tree can be washed in the winter using an oily wash, (Winter Tree Wash) trees can also be grease banded, this will stop insect pests climbing the tree, place the grease bands about 45-60cm (18 & 24 inches) from soil level.