Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Guide to New Zealand's freshwater invertebrates

Water measurer ( Hydrometridae : Hydrometra )

Diagnostic features

Hydrometra bugs are not likely to be confused with any other aquatic insect. They have a long body, long legs and long head, with the eyes located part way along the head.

Typical habitats

Hydrometra bugs live on the surface of the water, usually in ponds or wetlands, and most commonly in the North Island.


They are predators, feeding on other pond invertebrates. Overseas Hydrometra are known to feed on other pond predators including dragonflies and dytiscid beetles.

Indicator value

Hydrometra are only likely to be found on the water surface of stagnant (or near stagnant) waters. Because they don’t live under water they may have limited value as water quality indicators. They have not been assigned any tolerance values.