Small grain-Hessian fly

Mayetiola destructor

Pest description and crop damage Adult is a delicate, mosquito-like fly with a reddish brown to dusky black body. Insects overwinter in puparial "flaxseed" stage in stubble, volunteer wheat, and fields seeded before mid October.

Larval feeding at or near the crown stunts plants and reduces yield. Greatest damage is usually to wheat, but barley and rye also are attacked. Oats are free of this pest.

Management-cultural control

Deep plowing soon after harvest is helpful if soil conditions permit this practice. Direct seeding systems in the drylands of Washington and Idaho prevent deep plowing. Follow cultural practices that lead to optimum production. Winter wheat seeded after mid October is usually free of this pest. Spring wheat seeded behind failed fall-seeded wheat is especially prone to attack.

Management-chemical control

Seed treatments

Seed treatments applied to wheat and barley seed may help control Hessian fly.

  • clothianidin (NipsIt Inside) at 0.07 lb ai/100 lb seed on-farm application. Do not exceed 0.2 lb ai/a clothianidin per year. Wheat only
  • imidacloprid (Gaucho 600F) at 0.8 to 2.4 fl oz (0.031 to 0.094 lb ai) per 100 lb seed. Do not graze or feed livestock on treated areas within 45 days after planting.
  • thiamethoxam (Cruiser 5FS) at 0.75 to 1.33 fl oz (0.029 to 0.052 lb ai) per 100 lb seed. Do not graze or feed livestock within 45 days.

Foliar sprays

  • gamma-cyhalothrin (Declare) at 0.01 to 0.015 lb ai/. PHI 30 days. REI 24 hr. Maximum 0.03 lb ai/a per season. Do not graze or forage within 7 days of application. Do not feed straw within 30 days. Apply when adults emerge.
  • lambda-cyhalothrin (Silencer, Warrior II) at 0.02 to 0.03 lb ai/a. PHI 30 days. REI 24 hr. Apply when adults emerge. Do not graze or forage within 7 days of application. Do not feed straw within 30 days of last treatment. Do not exceed 0.06 lb ai/a per season.
  • lambda-cyhalothrin+tebuconazole (Crossover) at 0.14 lb ai/a. PHI 30 days. REI 24 hr. Do not exceed 0.11 lb ai/a tebuconazole or 0.06 lb ai/a lambda cyhalothrin per season. Feeding restrictions apply. Do not exceed 8 fl oz/a or 0.139 lb ai/a per season.
  • lambda-cyhalothrin/thiamethoxam (Endigo ZC) at 0.056 to 0.072 lb ai/a. PHI 30 days. REI 24 hr. Retreatment interval 7 days. Do not exceed 0.06 lb ai/a lambda-cyhalothrin or 0.125 lb ai/a thiamethoxam per season. Make applications when adults emerge. Barley only.
  • pyrethrin-There are several pesticides containing various amounts of pyrethrins. Check each label for the use and amount needed. Some formulations are OMRI-listed for organic use.