Preventing rat-tailed maggot incursion into dairy sheds

Abstract

Rat-tailed maggots are the larvae of hover flies (Diptera: Syrphidae), of which there are about 40 species in New Zealand, many of them native. The adults are important pollinators and the larvae live in water and mud, feeding on rotting organic matter. High concentrations occur in dairy effluent bunkers and become health and sanitary issues when prepupal larvae seeking suitable pupation sites exit bunkers and invade nearby dairy sheds. Replicated small scale model bunkers were set up to test barrier methods that could prevent maggots entering sensitive areas and divert them to suitable pupation sites. Known numbers of migratory prepupal larvae were placed in the model bunkers and their movements recorded over a timed period. Both round piping and angular strips proved effective barriers, while soil, sand and sawdust were all equally attractive as a pupation medium.