How to Manage Pests

Pests in Gardens and Landscapes

Bulb flies

Narcissus bulb fly—Merodon equestris
Lesser bulb fliesEumerus spp.

Adult bulb flies are stocky, hairy flies, blackish to dark green with pale yellow, orange, or gray markings.  Adult bulb flies look like small bumble bees and may also resemble other beneficial species.  On warm sunny days, adults often hover around blooming plants, where they feed on pollen and nectar.  Bulb fly larvae are plump, wrinkled, dirty yellow, gray, white, or brownish maggots with a short brown or blackish breathing tube at their rear. Maggots of several species of flies infest bulbs of all types, including daffodil, iris, lily, and tulip.

Life cycle

Damage

Larvae feed in bulbs, causing yellow foliage and stunted plants.  If infested, large bulbs produce fewer leaves and distorted growth.  Instead of a large shoot, small leaves may emerge in a ring around the central growing point that has been killed by a larva.  Blooms and small bulbs often die.  Narcissus bulb fly attacks healthy plants; lesser bulb flies prefer bulbs and rootstocks that are already diseased or decayed.

Solutions

Prevention is the most effective bulb fly control strategy.  Purchase and plant only pest-free bulbs.  Handle bulbs carefully to avoid injury. Remove and destroy infested bulbs and plants as soon as you find them.


Statewide IPM Program, Agriculture and Natural Resources, University of California
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