Seasonal development
and life cycle—Bulb flies
The adult lays an egg in spring or summer on exposed bulbs or stems at or near the base of plants. After 5 to 14 days, the egg hatches and a larva wriggles down into the soil or moves down along the outside of the bulb. It feeds on the bottom of the bulb where the roots emerge then enters and feeds inside the bulb. The larva develops through three instars over a period of 9 to 10 months. In spring the larva pupates in a brownish case inside the bulb, or it emerges and pupates nearby in topsoil. Pupation takes 4 to 8 weeks, after which the adult emerges, mates, and females lay eggs. Adults live about 2 to 3 weeks.
| 
Bulb fly life cycle (by Valerie Winemiller, adult from C.F. Doucette. 1959. The Narcissus Bulb Fly. USDA Leaflet 444.)
|
