Integrated Pest Management Guide

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SYRPHID FLIES (DIPTERA: SYRPHIDAE)

Adult syrphids, also called hover flies, mimic the movements and colourings of bees and wasps. These colours warn potential predators away from bees and wasps, and accomplish the same effect for the harmless syrphid flies that possess no stinger. Adult syrphids feed on pollen, nectar and the sugary secretion called "honey dew" produced by aphids. Larvae are very efficient predators.

The adult female moves up and down a plant, searching for aphids while hovering in one spot. After the female has located a colony, she deposits the eggs in small batches among the aphids. Depending on the species, the female lays between 400 - 1000 oblong, white eggs that hatch after a few days.

The tiny, blind larvae hunt for aphids by raising the front part of their bodies and swinging back and forth until they bump into their victim. On contact with an aphid, the syrphid larva uses its sharp mouthparts to pierce the aphid, lift it up and suck it dry. One syrphid larva can destroy up to 400 aphids in its 7 - 10 days of life. The full-grown larvae pupate in the soil or rolled-up leaves. Metamorphosis takes about 7 -8 days, after which the adult flies emerge. Depending on the climate, 3 - 7 generations a year are possible. Syrphids also play an important role as pollinators and can often be observed in and around cranberry
beds.


Syrphid fly