Flyfishing Entomology


Life Stage Characteristics



Beetle (Aquatic)


        -  Head: usually distinct

        -  Eyes: poorly developed

        -  Mouthparts: for chewing, sometimes modified for sucking

        -  Thoratic legs: usually present

        -  Abdomen: 8-10 segmented

        -  Lateral and/or terminal filiments may be present

        -  Instars: 3-8


(no illustration available)


    -  Head: has chewing mouthparts

    -  Eyes: well developed

    -  Forewings: modified into hardened covers

    -  Tarsi: 3-5 segmented

    -  Size: highly variable


There are (18) families of aquatic beetles, which come in many shapes and sizes. The larva and adult illustrations above are of predaceous diving beetles.

Larvae usually have a distinct head, chewing mouthparts, and poorly developed eyes. Wing pads are absent, and thoracic legs are usually present. At maturity, different aquatic beetle species vary in size from 2 mm – 60 mm (2 2/5").

Pupae are mummy-like forms that are generally not aquatic.

Adults are hard bodied and oval to elongate, with chewing mouthparts and well-developed eyes. The fore wings are hardened covers that usually meet and cover the hind wings and the abdomen.  Depending on the species, they can vary in size from 1 mm - 40 mm (1 3/5").

Created: 08/04/2004   Last modified: 10/31/2014   www.FlyfishingEntomology.com