Left: Geneticist's friend Drosophila melanogaster Right: spotted-wing Drosophila Drosophila suzukii
The spotted-wing drosophila Drosophila suzukii is unusual because it causes problems in the garden by damaging the fruit of strawberries, raspberries, currants, grapes, cherries and plums. It is new to Britain and Ireland, arriving from south-east Asia in 2012 and becoming noticed as a problem in 2015.
Compost bin flies are most active during spring to autumn but some may be present as adults in winter. Eggs are laid on the decomposing plant material. The larvae feed on decaying plant material and the fungi and bacteria associated with such material.
When the larvae have completed their feeding they pupate and later emerge as adult flies.
Role of compost bin flies in gardens
The larvae of compost bin flies, along with other insects, woodlice, millipedes, earthworms, fungi and bacteria, are a vital part of the process that converts plant waste into compost ready for use in the garden. Some people find it disconcerting to be greeted by a plume of small flies rising up out of the bin when the lid is removed. If this is a problem, remove the lid and walk away. After about five minutes, the flies will have settled back in the bin, more plant material can be added and the lid put back in place.
Other sources of information
on scarid flies https://www.rhs.org.uk/advice/profile?pid=804
Withers, P. (1989) Moth flies, Diptera:Psychodidae. Dipterists Digest vol 4 An identification key published by the Dipterists Forum
Freeman,P. (1983) Sciarid flies - Diptera, Sciaridae. RES Handbooks for the identification of British Insects. Volume 9 part 6.
Page drafted by Andrew Halstead, reviewed by Andrew Salisbury, edited by Steve Head