Flyfishing Entomology


Life Stage Characteristics
Alderfly (Megaloptera - Sialidae)

   -   Abdominal segments 1-7 each have a pair of lateral filaments
   -   Abdomen: ends in a single  long filament
   -   Color: light tan to brown
   -   Length: 6mm - 18 mm
   -   Growth instars: 10-11
   -   Larva crawls out of water to pupate, so pupa is not available to fish
   -   Pronotum: thick, as wide or wider than head
   -   Wings: held tent like over body when at rest
   -   Antennae: body length
   -   Tails: absent
   -   Body and wings: smoky-gray or black
   -   Length: 6 mm - 16 mm
Alderflies constitute a single family.  The alderfly larva’s primary distinguishing characteristics are its lateral gill filaments and single tapered filament at the end of the abdomen.

The alderfly pupa isn’t available to fish, as the larva crawls out of the water onto shore before pupating.

The alderfly adult (when at rest) holds its wings tent-like, similar to a caddisfly adult.  However, alderfly adults can be easily differentiated from caddisfly adults by the length of their antennae.  Antennae of alderfly adult are only the body length, as opposed to the caddisfly adults, whose antennae are as long as (or longer than) the body length.

Created: 08/04/2004   Last modified: 05/21/2010    www.FlyfishingEntomology.com