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Insects: DIAGNOSTICS

Horticultural Diseases and Pests - Alphabetically
Horticultural Diseases and Pests - by Host

Bagworms

Hosts:

In Oklahoma the most common hosts are eastern red cedar, other junipers, and arborvitae.

Description of Insect:

Full-grown larvae are 3/4 to one inch long, dark brown with white to yellowish heads and a black spotted mid-section.

Life Cycle:

Bagworms overwinter as eggs inside the bags of mated females. The eggs hatch in late spring (May to early June) and the larvae begin feeding and constructing their protective case. As the caterpillars grow in size, the bag is constantly enlarged. Male larvae pupate in late summer and they emerge from their bags as black moths with furry bodies, feathered antennae, and clear wings with a wing span of almost one inch. The female is a wingless moth that remains in a worm-like form and never leaves the bag. She is fertilized by the male, lays 500 to 1,000 eggs inside the bag, and then dies. There is one generation per year.

Symptoms:

Bagworms will attack and defoliate most evergreen and deciduous trees and shrubs, but prefer arborvitae, red cedar, juniper, bald cypress, several species of pine, and boxelder. Bagworms live inside a spindle--shaped bag which they construct while they are in the larval or caterpillar stage. The bags are dragged with the caterpillars wherever they go and are made of silk and bits of foliage.

Control:

A single bagworm does relatively little harm as it feeds on leaves but can defoliate a tree when infection is high. When practical, bagworms can be removed with scissors or a sharp knife. Insecticides are effective, particularly when applied in June or early July when the bagworms are small.