Onion fly

Symptom

Onion flies or onion maggots are serious pests of onion crops. They become active in early spring (around March to May). Begin monitoring shortly after planting or transplanting. The larvae (maggots) cause the primary damage by feeding on underground parts of the plant. In young plants, leaves suddenly wilt, turn yellow, and collapse. Plants may pull out easily from the soil, with rotted roots or base. Larvae burrow into the base of the onion bulb or stem, causing soft rot. Affected bulbs may have a wet, mushy, or slimy texture with a foul smell. Visible small holes or tunnels in the bulb indicate larval feeding inside. Damage provides entry for secondary pathogens, such as bacteria and fungi. If infestation occurs later, plants may grow slowly, have yellow leaves, or fail to form proper bulbs. White, legless maggots may be found inside the bulb or at the base of the plant. Usually found in groups, unlike cutworms or other pests.