The whitish eggs are slightly curved with their posterior bluntly rounded. Mature larvae range from 0.2 to 0.25 inch in length, are white to whitish yellow, cylindrical, and taper anteriorly.
Pupae are small brown capsules.
Slow emergence and poor stand establishment are signs of seedcorn maggot activity. Where slow, spotty emergence is observed, dig up seeds and inspect for maggot feeding. Soil and weather conditions such as cool soil temperature and periods of excessive moisture favoring slow seed germination and seedling emergence increase susceptibility to seedcorn maggot infestation. To reduce attractiveness of a field to egg-laying adults, disc or plow early in the season, incorporating residues from a previous crop and destroying weed growth. Plant under ideal soil and weather conditions to assure rapid seed germination and minimize the seedcorn maggot problem.