Pest profile

Bulb Flies

Merodon equestris and Eumerus species (shown: lesser bulb fly, E. funeralis) · Diptera: Syrphidae[2]

Bulb fly maggots tunnel inside bulbs such as daffodil, iris, lily and tulip; buying clean bulbs is the best prevention.[1]

Lesser bulb fly, a small dark hoverfly with pale markings, seen from above
Lesser bulb fly, a small dark hoverfly with pale markings, seen from above. (c) Bill Keim, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are stocky, hairy, blackish to dark green flies with pale markings that look like small bumble bees.[1]
  • Larvae are plump, wrinkled, dirty white to brownish maggots with a short dark breathing tube at the rear.[1]
  • Adults hover around blooming plants on warm, sunny days, feeding on pollen and nectar.[1]

Look-alikes

Look-alikeHow to tell them apart
Bumble bees and other beneficialsAdult bulb flies resemble small bumble bees and some beneficial flies.[1]

Where it lives

Maggots of several fly species infest bulbs of all types.[1]

US map: public records from 37 states since 1990 (GBIF).

Biology and life cycle

Eggs are laid in spring or summer near the base of plants and hatch in 5 to 14 days.[1]

Larvae feed in the bulb for 9 to 10 months and pupate in spring; adults live about 2 to 3 weeks.[1]

Damage and signs

  • Infested bulbs yield yellow, stunted plants, rings of small leaves, and blooms or small bulbs that die.[1]
  • Narcissus bulb fly attacks healthy bulbs; lesser bulb flies prefer bulbs that are already diseased or decayed.[1]

Health risk

They feed in bulbs; UC IPM mentions no risk to people.[1]

Control

Prevention

Buy and plant only pest-free bulbs, and handle them carefully to avoid injury.[1]

Sanitation

Remove and destroy infested bulbs and plants as soon as you find them.[1]

Common questions

Why did my daffodils come up as a ring of small leaves?
A bulb fly larva may have killed the central growing point.[1]
Are the fuzzy flies at my flowers bees?
Some may be bulb flies, which look like small bumble bees.[1]

Sources

  1. University of California Statewide IPM Program, “Bulb Flies (Pests in Gardens and Landscapes).” ipm.ucanr.edu/PMG/GARDEN/FLOWERS/INVERT/bulbfly.html (accessed 2026-10-06)
  2. iNaturalist, “Eumerus funeralis taxon page (order and family).” www.inaturalist.org/taxa/465857 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.