SEED-CORN MAGGOT (on lima bean)

A, Life stages: a. egg; b. lama; c, pupa; d, adult (all about seven times natural size). B, Injury to cotyledon. C, Injury to plumule. D, Young plant with part of damaged stem cut open to expose maggots inside. (B. C, and D, about natural size.)

SEED-CORN MAGGOT

The seed-corn maggot attacks the sprouting seeds of beans, peas, and corn and potato seed pieces. The adults look like small house flies. They lay their eggs in the soil on or near the food plants. The white, legless maggots hatch in 2 or 3 days and feed on decaying plants or seed or on the soft sprouting seed. They usually destroy the germ of the seed so that no plants are produced. Damaged beans often have root systems that develop and push the seeds out of the soil as ballheads with no foliage. In 2 to 3 weeks the maggots become full-grown and pupate. After another week or two the adults emerge to repeat the cycle. The insect is distributed throughout the United States and attacks a wide variety of plants.

Control: As soon as maggot injury is discovered, replant. Avoid organic fertilizer in the seeded row. Partly decayed vegetable matter attracts the flies; soils containing such material are likely to become infested with maggots. Plant seed shallow in such lands, and prepare the seedbed so as to promote rapid germination. Plant the seed when the soil is warm. Cool, wet periods retard seed germination and promote injury by maggots.

Damage may be prevented by delaying planting until the maggots of the first generation have become full-grown and are entering the pupal stage. The plants will then have time to come up before maggots of the next generation appear.

Seed-corn maggot damage to potato seed pieces is prevented by allowing the cut seed pieces to heal before planting. The maggot attacks the sound pieces of potato only where the skin is broken or the surface is injured.

The treatment of seed with insecticides like chlordane has given promising results, but the method has not been perfected.