The larvae bore into the underground stems and consume the interior of bulbs, reducing stands and decreasing uniformity. Plant mortality may also occur, plus internal soft rotting of infested bulbs. Female flies live approximately six weeks and lay their eggs at the base of the host plant or on the soil. They produce an average of 270 eggs. The adults are abundant all year long, however, seedcorn maggot damage is most severe in the early spring when the weather is cool and the soils are wet.
Cabbage maggots can cause damage all summer long.
Eggs hatch in one to nine days, depending on the soil temperature. Larvae develop rapidly with warm temperatures. Within one to three weeks mature maggots pupate. Adult flies emerge approximately one to three weeks later. Prevention is the best management strategy.