Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Guide to New Zealand's freshwater invertebrates

Moth fly ( Psychodidae : Psychodidae )

Diagnostic features

Psychodid flies have small larvae that are easily distinguished by the combination of a non-retractile head, a respiratory siphon at the tip of the tail, and many small sclerotised (hardened and pigmented) plates along the length of the abdomen.

Typical habitats

Psychodid larvae can be found along stream margins, amongst decaying vegetation, and sometimes amongst “sewage fungus” growths in polluted waters.


Psychodids eat decomposing organic matter, probably mostly rotting vegetation, associated decomposer microbes and aquatic algae.

Indicator value

Psychodid larvae can be found in good quality streams, but they can also thrive in quite polluted streams. Their ability to live in “clean” and polluted waters is reflected by the wide ranging tolerance values of 1 (hard bottom sites) and 6.1 (soft bottom sites).