Uglynest caterpillar

Distribution

Canada

Canada and the northeastern United States

Micro-habitat(s)

Leaf, Bark

Damage, symptoms and biology

The ugly-nest caterpillar is a native species that is widely distributed throughout Canada and the northeastern United States. It may be abundant some years and then scarce for long periods. The insect feeds mostly on chokecherry and black cherry, but also counts roses and hawthorn as favourite hosts. During outbreaks it often feeds on trembling aspen, poplars, and birches. It is of little economic importance, except that it spins unsightly webs on its hosts and these are often noticeable along roadsides.

The adult moth has a wing span of about 25 mm. It is dull orange and the front wings are marked with irregular brownish spots and transverse bluish bands. It emerges from late July to the end of August and the females lay their eggs in masses on the bark of shrubs and young trees, near the ground. The eggs hatch the next spring in late May or early June. The larvae tie the leaves together, thus forming a nest or web within which they live and feed. The size of the nest is increased as the larvae become larger and often whole chokecherry trees are completely covered. Most of the caterpillars complete their growth and develop into the pupal stage in the first two weeks of July. Pupation takes place within the web and before the adults emerge, the pupae work their way to the outer wall of the web. There is one generation each year.

Other information

Natural enemies can normally be relied upon to control the occasional outbreaks of the ugly-nest caterpillar. The most satisfactory way to control the insect after the webs have been formed is to cut off the webs and burn them.

Main host(s)

Birch, black cherry, choke cherry, hawthorns, poplars / aspens / cottonwoods, rose, trembling aspen