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Guide to New Zealand's freshwater invertebrates
Spiral cased caddis
(
Helicopsychidae
: Helicopsyche
)
Diagnostic features
Helicopsyche caddis larvae construct a small mobile case made of sand grains arranged in a spiral. At first glance they might be mistaken for small snails, but the legs of the caddis larva can be seen when the larva moves.
Typical habitats
Helicopsyche larvae are common in many stony or gravelly, bush-covered streams.
Feeding
They are “collector-gatherers”, feeding on a range of organic matter accumulating on stream beds.
Indicator value
An abundance of Helicopsyche larvae indicates good habitat and water quality conditions, especially if mayfly or stonefly groups are also abundant. They have high tolerance values of 10 (hard bottom sites) and 8.6 (soft bottom sites).
