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Free-living caddis

Guide to New Zealand's freshwater invertebrates

Free-living caddis ( Hydrobiosidae : Costachorema )

Extensive pigmentation on the head
Prosternal plate much wider than long

Diagnostic features

The New Zealand hydrobiosid caddis larvae have pincers on their forelegs. Costachorema larvae are often first recognised by the extensive black pigmentation on the top of the head. Under the prothorax (first segment behind the head) between the forelegs is a prosternal plate that is much wider than long.

Typical habitats

Costachorema larvae are common in stony streams and rivers, in bush covered and farmland areas.

Feeding

They are predators, feeding on other stream invertebrates.

Indicator value

An abundance of Costachorema larvae indicates good water quality, particularly where mayfly and stonefly nymphs are also abundant. They have tolerance values of 7 (hard bottom sites) and 7.2 (soft bottom sites).