Whirligig beetles

Code QC100000

The larva of whirligig beetles (Coleoptera: Gyrinidae) are long and parallel-sided, resembling a megalopteran larva. The head and thorax are similarly shaped and similarly sclerotised to those of Megaloptera and the abdomen carries paired lateral gills but no central terminal filament. The most likely mis-identification is thus with Corydalidae.

The major external difference between Corydalidae and Gyrinidae is that the former carries one pair of gills on each of segments 1-8 whereas the latter carries one pair on each of 1-8 plus two pairs on segment 9. The gills of Gyrinidae typically are fringed with setae, unlike the bare gills of Corydalidae. If confirmationary evidence is required, the labrum and clypeus are distinct in megalopteran larvae but fused as a single sclerite in Gyrinidae, and the megalopterans have a 3-segmented not a 2-segmented labial palp.