Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Guide to New Zealand's freshwater invertebrates

Double gill mayfly ( Leptophlebiidae : Arachnocolus )

Diagnostic features

Arachnocolus mayfly nymphs have double gills, long thin legs (particularly the femur and tibia), and a generally pale body colour.

Typical habitats

Arachnocolus larvae are most abundant in bush-covered, gravelly streams with cool and well aerated water.


Leptophlebiid mayflies feed by scraping diatom algae and other organic matter from stone surfaces.

Indicator value

Arachnolocus are not often found in high abundance, but they are indicative of good habitat and water quality, especially if other mayfly or stonefly groups are abundant. Arachnolocus has tolerance values of 8 (hard bottom sites) and 8.1 (soft bottom sites).