Woolly Bear Caterpillar (Kansas Soybean)

Sampling method

Woollybears are hairy (woolly), yellowish or brown caterpillars up to 2 inches in length. Populations are often overestimated because the larvae and damage are striking. The smaller larvae often are observed feeding in groups on the underside of the leaves, which quickly become skeletonized and die. The larger, showy larvae tend to feed exposed on the upper leaf surfaces. In 2013, scattered populations developed to levels justifying control.

Chemical control



Alpha-cypermethrin (Fastac EC)

 1.3 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)

 1.5 to 2 lb. a.i./acre

Chlorantraniliprole (Prevathon)

 14.0 to 20.0 fl oz/acre

Chlorpyrifos (numerous products)

 Check label, but generally 1 to 2 pints/acre

Chlorpyrifos plus gamma-cyhalothrin (Cobalt)

 11.0 to 26.0 fl. oz./acre

Cyfluthrin (Tombstone)

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

Deltamethrin (Delta Gold)

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

Esfenvalerate (Asana XL 0.66)

 0.015 to 0.03 lb. a.i./acre (2.9 to 5.8 fl. oz.)

Gamma-cyhalothrin (Proaxis, Declare)

 0.0075 to 0.0125 lb. a.i./acre (1.92 to 3.20 fl. oz.) (See label for Declare)

Imidacloprid plus cyfluthrin (Leverage)

 2.8 fl. oz./acre

Lambda-cyhalothrin (numerous products)

 0.015 to 0.025 lb. a.i./acre

Lambda-cyhalothrin chlorantraniliprole (Besiege)

 5.0 to 8.0 fl. oz./acre

Lambda-cyhalothrin plus thiamethoxam (Endigo ZC)

 3.5 to 4.0 fl. oz./acre

Methoxyfenozide (Intrepid 2F)

 0.06 to 0.12 lb. a.i./acre (4 to 8 fl. oz)

Permethrin (multiple products)

 0.05 to 0.10 lb. a.i./acre

Spinosad (Blackhawk)

 0.038-0.050 lb. a.i./acre (1.7 to 2.2 oz/acre)

Thiodicarb (Larvin EC)

 0.25 to 0.4 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



































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