Characteristics

Hydroscaphids are minute beetles. The following illustration shows an adult Hydroscapha (see arrow) on algae in its native habitat. The coin is a United States dime.

Here is a third-instar larva of Hydroscapha natans, from southern Arizona, crawling through algae:

The shiny white line protruding from the left side of the first abdominal segment is one of the spiracular gills.

Hydroscapha natans pupates within its last larval skin. The pupa, in the old skin, then floats at the surface of the water, held there by surface tension, as shown in the following figure: