Linden looper

The linden looper overwinters in the egg stage on host trees. In May, or as soon as the buds begin to open, the larvae emerge and begin feeding on the new foliage. Larvae are light brown to yellow, with a broad, bright yellow stripe along each side, and ten, wavy, narrow black lines along their back. The head may vary from yellow to rusty-brown. By late June or early July, the larvae are approximately 37 mm long and are full grown. They crawl or drop to the ground and tunnel into the soil to pupate. Adult moths emerge in October or November. Male moths have a wingspan of 37- 42 mm. The forewings are a light buff colour, marked with two, brown, wavy, transverse bands. The forewings also have a sprinkling of brown dots, and at times, a diskshaped spot. The hind wings are lighter in colour and are marked with a faint, disk-shaped spot. Females are wingless and are approximately 13 mm long. They vary in colour from light grey to brownish and have two rows of large, black spots on their back. After mating, the females crawl up the tree and deposit eggs singly or in clusters under loose bark or in crevices on the trunks and limbs. Overwintering eggs are oval and yellowish-brown. In Canada, there is only one generation a year of the linden looper.

Damage

The linden looper causes damage by defoliation during the larval stage. Large scale control measures have never been required because of natural control by parasites and diseases.

Control

When populations of linden loopers grow because of an insignificant amount of natural enemies, other control methods can be used. One method to control the pest on a small number of trees is by banding. Banding prevents the wingless females from crawling up the trees to lay eggs. In late September, before adult emergence, a 10 cm band of paper-backed insulation or cotton batting and tar paper (paper side out) is attached to the tree at a one meter height. A thin layer of sticky adhesive (Tanglefoot®) is applied to the band. Linden loopers on a large number of trees or in a shelterbelt can be sprayed with Bacillus thuringiensis during the early larval stage. Bacillus thuringiensis is a bacterial insecticide that is non-toxic to beneficial insects. Recommended chemical insecticides are carbaryl and methoxychlor.