Garden Webworm (Kansas Soybean)

Sampling method

The garden webworm, a common webworm, is slender and green with three dark spots arranged in a triangle on the sides of each body segment. Each spot supports at least one hair. Larvae skeletonize the foliage in the protected, webbed area. If disturbed, larvae move backward rapidly. Peak damage occurs July through August with multiple generations possible. The edges of some soybean fields in northeast Kansas became infested during 2001 with high numbers of webworms moving out of harvested alfalfa fields. Many fields in SE and central Kansas required treatment in 2009, and again in 2010.

Chemical control



Alpha-cypermethrin (Fastac EC)

 2.8 to 3.8 fl. oz./acre

Beta-cyfluthrin (Baythroid XL)

 0.0125 to 0.022 lbs. a.i./acre (1.6 to 2.8 fl. oz.)

Bifenthrin plus imidacloprid (Tempest)

 0.08 to 0.095 lb. a.i./acre (5.1 to 6.1 fl. oz./acre)

Carbaryl (Sevin)

 1.0 to 1.5 lb. a.i./acre

Chlorpyrifos plus gamma-cyhalothrin (Cobalt)

 11.0 to 26.0 fl. oz. of product/acre

Chlorpyrifos plus zeta-cypermethrin (Stallion)

 5.0 to 11.75 fl. oz./acre

Cyfluthrin (Tombstone)

 0.025 to 0.044 lb. a.i./acre (1.6 to 2.8 fl. oz.)

Deltamethrin (Delta Gold)

 0.018 to 0.022 lb. a.i./acre (1.5 to 1.9 fl. oz.)

Gamma-cyhalothrin (Proaxis, Declare)

 0.0125 to 0.015 lb. a.i./acre (3.2 to 3.84 fl. oz.) (See label for Declare)

Lambda-cyhalothrin (numerous products)

 0.025 to 0.030 lb. a.i./acre

Lambda-cyhalothrin chlorantraniliprole (Besiege)

 8.0 to 10.0 fl. oz./acre

Lambda-cyhalothrin plus thiamethoxam (Endigo ZC)

 4.0 to 4.5 fl. oz./acre

Permethrin (multiple products)

 0.1 to 0.2 lb. a.i./acre

Zeta-cypermethrin (Mustang MAXX, etc.)

 0.0175 to 0.025 lb. a.i./acre (2.8 to 4.0 fl. oz.)

Zeta-cypermethrin plus bifenthrin (Hero)

 4.0 to 10.3 fl. oz. of product/acre


Content authors


This content may not be suitable for states other than Kansas.