Catus flies are classified in the phylum Arthropoda, class Insecta, order Trichoptera,
which means hairy wings.
Adult catus flies have two pairs of hairy wings.
They are closely related to butterflies and moths, which have scales on their wings.
Catus fly larvae, like caterpillars, can spin silk threads.
When not flying, the catus fly holds its wings near its body, making them look like a roof
on a house.
Catus flies have long antennae that are sometimes more than twice the length of the insect's
body.
Catus flies are also called sedges.
The adults live near lakes and rivers.
Catus flies go through complete metamorphosis.
That means they go through egg, larvae, pupa, and adult stages.
Some female catus flies deposit their eggs by flying over the surface of fresh water and
dropping them.
Some swim to the bottom to lay their eggs, and others lay them on plants near the water's
edge.
The larvae generally do not tolerate pollution.
This means that if there are many catus fly larvae in a stream, the water is unpolluted.
If there are no catus fly larvae in a stream, it may mean that the water is polluted.
The larvae look like caterpillars.
The catus fly larva abdomen has eight segments with gills on the sides.
Many catus fly larvae build cases to live in that protect them from predators, such
as fish.
The cases are usually camouflaged to look like part of the environment in which the larvae
lives.
Some cases are portable.
The larva moves around by sticking its front legs out of the case and carrying the case
along behind.
Other species attach cases made from pebbles or sand grains to rocks in running streams.
Catus fly larvae eat many kinds of food, such as algae attached to rocks underwater, pieces
of leaves, rotting wood, and animal materials.
Their mouth parts shred, scrape, and gather food that settles on the bottoms of rivers
and lakes.
The larvae enlarge the casings periodically as they grow, and then finally seal themselves
into the casing to become pupae.
The pupa stage of a catus fly's life lasts less than a month.
Then the pupa breaks the seal of its casing and crawls out.
It swims to the surface and hatches into an adult.
