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Stony cased caddis

Guide to New Zealand's freshwater invertebrates

Stony cased caddis ( Philorheithridae : Philorheithrus )

Legs designed for grasping

Diagnostic features

Philorheithrus caddis larvae construct robust cases made of coarse sand grains. Each of the three thoracic segments have hard (“sclerotised”) plates. The fore legs and mid legs are raptorial (designed for grasping prey).

Typical habitats

Philorheithrus larvae are most common in fast flowing, cold water streams, particularly in mountainous areas.

Feeding

They are predators of other stream invertebrates.

Indicator value

The presence of Philorheithrus larvae is an indication of good habitat and water quality, particularly where a range of mayflies or stoneflies is also present. They have tolerance values of 8 (hard bottom sites) and 5.3 (soft bottom sites).