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Caddisflies are one of the largest groups of aquatic insects. Their closest relatives are butterflies and moths, and adult caddisflies look somewhat like moths.

There are about 275 species of caddisflies in Alberta.


Caddisfly larvae live in every kind of water habitat, from cold mountain streams to small and temporary prairie puddles.

Reproduction and Growth

  • A caddisfly may lay several hundred eggs during the summer.
  • After hatching, the larvae build and live in cases covered with small sticks or stones.
  • As they grow, the cases are made longer and wider. When danger threatens, the larvae retreat inside the cases.
  • Caddisfly larvae feed on small animals and plants, and overwinter as young larvae.
  • The larvae turn into pupae the next summer. The pupae float to the surface, and the adults emerge and fly away.
  • Caddisfly larvae are an important fish food. The best trout streams have many larvae on their bottoms.


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Updated: Apr 8, 2009