Description

Adult seedcorn maggots resemble house flies but the body is somewhat slimmer and at rest, wings are held more backward directly over the abdomen. The damaging form is the larval stage. Larvae can be found attacking germinating seed and at maturity are creamy white and about 1/4 in. long (Photo 5-8). A distinct head and legs are lacking.

Distribution, damage and impact

Seedcorn maggots occur worldwide and throughout Arkansas. Many crops are attacked including field corn. Most problems in field corn occur in fields high in organic content. Freshly plowed fields with decaying grass and weeds are especially attractive to adult flies which lay eggs near the decaying plant material. When corn is seeded into this ground, the developing maggots often move to the corn seed and can reduce germination, seedling vigor and stand.

Life History

In northern states the seedcorn maggot overwinters as a pupa within the soil. All stages can be found during mild winters in Arkansas. As spring nears adults seek decaying organic matter for egg deposition. After hatching larvae feed for 1 to 3 weeks and pupate within the soil. Adults emerge and renew the cycle. Multiple generations occur each year in Arkansas.

Management

Planting in soils with fully decomposed plant material should reduce the attractiveness of the field to adult flies. Damage also is more severe in fields where seed are slow to germinate and where seedling growth is retarded. Thus, delaying planting until soil is warmer will reduce the impact of the seedcorn maggot. Treated seed and soil insecticides applied at planting are effective tactics. Use of insecticide sprays after maggot problems are detected on germinating seed or seedlings is of no benefit.

Insecticide recommendations for seedcorn maggot on field corn

See Table 5-1 for insecticide recommendations current at time of publishing. Current updated recommendations can be found in the Cooperative Extension Service publication MP-144 and on the world wide web at WWW.cdms.net/manuf/default.asp. Always follow instructions on pesticide labels.