Pollenia rudis

"The Cluster Fly"



Cluster flies invade houses in autumn often collecting in large numbers in windows. They winter in cracks of buildings and appear again in spring. These non-native flies were introduced because their larva were thought to be parasitic on the caterpillars of insect pests. Unfortunately they are parasites of earthworms a beneficial animal. Note the solid black thorax, house flies are striped.

Scanned from a specimen by A. Sinclair

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