Onion maggots (Delia aniqua) are particularly damaging to early season plantings like onions, garlic and carrots. The adults are gray flies which are smaller than houseflies. Onion maggots and cabbage root maggots looks very similar, but prefer different types of plants. Onion maggots are small, yellowish white, legless larvae. Onion maggots cause the most damage to early spring plantings by feeding on and tunneling through plant roots and bulbs. Onion maggots can cause stunted growth, yellowing, wilting and plant death and leave plants susceptible to rot diseases. There are several generations of onion maggots each year. Adults emerge in early spring, mate and typically lay their eggs at the soil line. Eggs hatch after just a few days and the larvae burrow into the soil where they feed for a few weeks. Onion maggots then pupate in the soil or in plant roots.