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Water scavenger beetle

Guide to New Zealand's freshwater invertebrates

Water scavenger beetle ( Hydrophilidae : Hydrophilid )

Adult with 3 enlarged antennal segments
Larval head often tipped backwards

Diagnostic features

Hydrophilid beetles (or water scavenger beetles) have larvae with soft abdomens that may be covered in bumps or long gills (see Berosus) depending on the genus. The larval head often appears tipped backwards, and long sickle-like jaws are often visible. The adults are active swimmers and generally oval in outline. The antennae have three enlarged segments at the tip (forming a “club”), but often the segmented palps (mouthparts) extend in front of the antennae.

Typical habitats

Hydrophilids can be found in weedy and stony, streams and ponds.

Feeding

The larval mouthparts suggest they are predators, but the adults may also scavenge on streambed detritus.

Indicator value

Hydrophilids occur in slow flowing waters with moderate to good water quality. They have tolerance values of 5 (hard bottom sites) and 8.0 (soft bottom sites).