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Taxonomic group

Hydroptilidae: Oxyethira

Diagnostic features

Oxyethira caddis larvae construct small, transparent, mobile cases shaped like an axe-head (hence the common name “axe-head caddis”). Each of the three thoracic segments has a hard (“sclerotised”) covering.

Typical habitats

Oxyethira larvae are most common in streams with limited shade, particularly at sites with abundant stream bed algae.


They feed on filamentous algae.

Indicator value

  • Hard bottom: 2
  • Soft bottom: 1.2

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

Abundances of Oxyethira larvae are usually recorded at sites with abundant streambed algae. Such algae is likely to be the result of nutrient enrichment, limited shade and a lack of recent high flow (algae scouring) events. They have low tolerance values of 2 (hard bottom sites) and 1.2 (soft bottom sites).