.......................  ....................  ...Fly Fishing Yellowstone National Park
04/30/12

New KISS Bug Series - Part 6
Bugs 101

Caddisflies:
Caddisfleis undergo complete metamorphoses. This simply means the caddisfly starts its life as an egg;
then changes to a larva; changes to a pupa; and finally changes to an adult. Caddisflies and midges have
one more stage of life to imitate than the mayflies and stoneflies.

Caddisfly Larvae:
The caddisfly larva comes in two basic forms - cased and uncased. To get a little more technical, they
come in five basic varieties - the free-living caddises, net spinners, saddle case makers, purse case
makers and tube case makers. The larvae, uncased or the cased variety, out of their cases look like
worms. They are segmented and have six legs and of course, a head.

Caddisfly Pupae:
When the larvae mature they enter the pupal stage of life for a relatively short time. The cased variety seal
themselves inside their cases. The free-living variety build retreats and stay there until the metamorphosis
is complete. You may be more familiar with a butterfly that lives in a cocoon in its pupa stage of life. When
the pupae come out of their retreats, they are called pharate adults. They are fully formed but they are still
in a skin with their wings compressed. This is when most of the species are most subject to being eaten by
trout. When we imitate the pupa, we are imitating the pharate adult. Most of them emerge on the surface of
the water but other species may rise to the surface and run across the water to the banks. Still others climb
out onto rocks or the bank and hatch into adults.

Caddisfly Adults:
The adult caddisflies mate in the bushes or on the banks or rocks. The females return to the water and lay
their eggs in different ways. Some deposit their eggs on the surface. Some skitter across the water,
knocking them off. Some crawl or dive to the bottom and deposit their eggs. Most caddisflies die away from
the water but others die during the egg-laying process. You should know the egg-laying habits of each
caddisfly genus, otherwise, you really do not know what you are doing when you imitate them.  

Copyright 2012 James Marsh
Long Horn Sedge
(Caddisfly). These
are common in
some of the streams
of Yellowstone
National Park.