Sorghum Webworm

The sorghum webworm is a hairy caterpillar with four reddish-brown stripes down its back. Full-grown larvae are only about ½- inch long. They are commonly seen feeding on grain in developing heads. They are usually associated with a sticky webbing in the area of their feeding.

Check grain heads for larvae. Examine a minimum of 50 plants throughout the field. Sets of 10 heads can be briskly shaken into a bucket or sweep net. Carefully look through the debris for larvae. Corn earworm or fall armyworm will also be found feeding in heads.

During heading, treat when an average of 3-4 or more larvae is found per grain head.


Management Options

Insecticide (Trade Names) for SORGHUM WEBWORMLb Active Ingredient per AcreAmount Formulation per AcrePerformance Rating
carbaryl (Sevin 80S)1 - 21.25 - 2.5 lb7
carbaryl (Sevin XLR 4)0.5 - 116 - 32 oz7
chlorantraniliprole (Prevathon 0.43 SC)0.05 - 0.0714 - 20 oz9
chlorantraniliprole, λ-cyhalothrin (Besiege)See label6 - 10 oz9
chlorpyrifos (Lorsban 4, Nufos 4)0.5 - 116 - 32 oz7
chlorpyrifos (Lorsban Advanced 3.775)0.47 - 0.9416 - 32 oz7
chlorpyrifos, γ-cyhalothrin (Cobalt Advanced)See label16 - 38 oz7
chlorpyrifos, Z-cypermethrin (Stallion)See label5 - 11.75 oz7
methomyl (Lannate LV 2.4)0.4524 oz7
spinosad (Blackhawk 36% WDG)0.038 - 0.0741.7 - 3.3 oz9
  • Planting early, before mid-May, may help avoid some damage from sorghum webworm.
  • Resistance to pyrethroid insecticides is well documented and has been observed in Tennessee. Use of alternative chemistries is generally suggested.