Pests of the Northeastern US

Editors: W.T. Wilsey, C.R. Weeden and A.M. Shelton

Onion Maggot (Delia antiqua) - Life Cycle

Click for larger image	Adults: Onion flies are slightly smaller than houseflies. They have longer legs, are more slender, and overlap their wings when at rest. The spring brood of onion flies emerges from pupae about mid-May. Peak flights occur about 2 weeks later in the northeast. Females begin laying eggs approximately 7-10 days after emergence. Onion flies can survive for 2-4 weeks and may lay several hundred eggs. The second or summer brood begins emerging in early July with peaks in mid to late July. Emergence of the final or fall flight begins in late August, peaks in early to mid-September, and may continue into October.	Click for larger image
	Eggs: The onion fly deposits white elongated eggs about 1/25 inch in length on the soil near the stem and occasionally on the young leaves and neck of the onion plant. Eggs hatch into maggots 2-3 days after being laid.
	Larvae: The legless maggots age tapered, creamy-white in color, and reach a length of about 1/3 inch. Maggots develop through three larval stages in 2 to 4 weeks depending on the temperature. Most newly hatched larvae crawl below the soil surface and feed upon the roots or burrow into the basal plate of the bulbs.
	Pupae: When full-sized, the maggot leaves the bulb and enters the soil to pupate at a depth of 1-4 inches. The pupa is chestnut brown and 1/3 inch long. First and second generation pupae remain in the soil for 2-4 weeks before adult emergence. Larvae of the third generation develop into pupae and pass the winter in that stag. Flies emerging the following spring constitute the spring flight.

Damage inflicted by onion maggot on onions

Some information on this page taken from Insects of Onions: Cornell Cooperative Extension factsheet number 102GFS750.50 authored by J. T. Andaloro and C. J. Eckenrode.

Maintained by Jason D. Plate. Last updated Mar. 8th, 2007.