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Sandy cased caddis (Zelolessica)

Taxonomic group

Helicophidae: Zelolessica

Diagnostic features

Zelolessica caddis larvae construct mobile cases of sand grains, sometimes mixed with plant fragments. The tail end of the case is angled, and has an opening wider than long. There is a fringe of long black hairs on the front edge of the pronotum (first segment behind the head).

Typical habitats

Zelolessica larvae are commonly found in bush covered, stony streams, often amongst aquatic mosses.


They are collector-gatherers, known to feed on organic detritus and streambed algae.

Indicator value

  • Hard bottom: 10
  • Soft bottom: 6.5

The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species

An abundance of Zelolessica larvae is an indication of good water quality, particularly where mayfly and stonefly nymphs are also abundant. They have tolerance values of 10 (hard bottom sites) and 6.5 (soft bottom sites).