Common Name: Dobsonflies / Alderflies

Greek Origins of Name: Megaloptera is derived from the Greek word “mega” meaning large and “ptera” meaning wings.

Spot ID Key Characters:

  1. Numerous crossveins near leading edge of wings
  2. Pleated area on hind wings for folding
  3. Antennae prominently visible

Spot ID Common Families:

Corydalidae — Dobsonflies
Sialidae — Alderflies

Development:  Holometabola i.e. complete metamorphosis (egg, larva, pupa, adult)
Taxonomy: Megaloptera is divided into two families:

  • Corydalidae (dobsonflies)
  • Sialidae (alderflies )

Distribution: Common worldwide, but seldom abundant.  Larvae are frequent inhabitants of streams and rivers.

The Megaloptera are always aquatic as immatures. They live under stones or submerged vegetation and feed on a variety of small aquatic organisms. Large species, often called hellgrammites, may require several years of growth to reach maturity. Adults usually remain near water, although they are attracted to lights at night. In most species, the adults live only a few days and rarely feed.  Adults have two pairs of membranous wings with an extensive pattern of veins and crossveins. At rest, the wings are folded flat over the abdomen or held tent-like over the body. The hind wings are pleated to allow for folding.  Most species are rather weak fliers.

Appearance of Immatures:

  1. Head well-developed with ocelli, antennae, and chewing or pinching mouthparts
  2. Three pairs of thoracic legs; tarsi 1-segmented; claws paired
  3. Thread-like gills on most abdominal segments

Appearance of Adults:

  1. Extensive branching of venation in all wings; crossveins abundant especially along leading edge (costal margin)
  2. Front and hind wing membranous, similar in size, but hind wings pleated for folding
  3. Antennae filiform, multisegmented
  4. Chewing mouthparts

Larvae of Megaloptera are important predators in aquatic ecosystems. They also serve as food for fish and other aquatic vertebrates.

Megaloptera families:

      • Corydalidae (Dobsonflies) — adults generally longer than 5 cm
      • Sialidae (Alderflies) — adults are smaller than dobsonflies