Life cycle of the Caddisfly

  • The female deposits eggs by swimming to the bottom or shaking them lose from the egg sac in the surface film of the stream.

    Cased Caddis lay a large number of eggs in a great blob of jelly. Caseless Caddis lay a small number in a sheet fixed to a rock and covered in a thin layer of jelly.

  • The eggs hatch into the larva form and depending upon the species may or may not build a case out of silk. Most will include stones and bits of plant in the construction!

    They will spend most of their life cycle in this larval stage.

  • The Cased Caddis larva eventually encase themselves in a cocoon. Caseless Caddis will make a rough shelter out of stones and debris. 

    Once in the cocoon, the larva transforms into the pupa over a few days. It sheds its outer skin to show the pupal skin beneath.

    After two weeks the pupa will cut open one end of the cocoon and will emerge to the surface. 

     

  • The pupa transforms quickly into an adult. Caddis are born dry so once they shed the husk their wings open and they fly quickly  away.

    Caddis adults live only for a few days and in that time they must lay their eggs for the cycle to begin again.

  • Thank you for information from the Freshwater Recorders and Schemes Project