Alfalfa Looper

Description

Adult: The wingspan of moths measures 35-45mm. Front wings are gray with various brown patches. There is a prominent silvery white or yellow mark at the center of each forewing. The edge of the front and hind wings have a series of dark spots.
Egg: Eggs are pale yellow, hemispherical, with thin vertical ridges.
Larva: Larvae are green with distinct white stripes along each side and three abdominal prolegs. They develop through five instars growing to 25-35 mm long.  
Pupa: Larvae spin a loose, whitish-silk cocoon. Pupae are a black-brown color and 18-20 mm long.

Life History

Alfalfa loopers overwinter as pupae in the soil. Adult moths emerge in late spring and can have up to four generations (a generation lasting 30-40 days) throughout the growing season.

Damage

Larvae initially feed by chewing irregular holes in the foliage. This can eventually skeletonize leaves.

Management

Cultural

Weedy fields, field borders, and high levels of plant residue provide food sources for alfalfa loopers. Thoroughly till crop residues and control weeds to reduce overwintering looper and feeding sites. Remove cool-season weeds along field edges to starve young caterpillars. Fall tillage can also help destroy or expose overwintering pupae. 

Biological

Many predators, parasites, and diseases attack alfalfa loopers. Bacillus thuringiensis (Bt) products can effectively control young larvae.