STREAM BUGS AS BIOMONITORS
Guide to Pacific Northwest Macroinvertebrate Monitoring and Identification
Jeff Adams
with Mace Vaughan and Scott Hoffman Black - The Xerces Society (www.xerces.org)

These hairy (tricho-) winged (-ptera) creatures are fairly closely related to moths and butterflies and represent one of the most diverse and easily spotted aquatic macroinvertebrate groups. Caddisflies are found in most aquatic habitats, and many have specific habitat and water quality requirements, making them good indicators of changes in stream condition. Caddisfly adaptations to the diverse habitats in which they live are most easily visible in the range of cases they construct.

The portable or stationary shelters that most caddisflies build for protection, feeding, and movement of water past the gills are probably the group's most remarkable feature. One especially unusual genus was initially reported as a snail by the scientist who discovered it! The shape and material of the cases often reflects the type of habitat in which they live. Some common and successful caddisflies only build a stationary shelter, and construct complicated silken fishing nets to capture drifting organic debris and tiny invertebrates.

Caddisflies are very important in stream food chains, eating both plant and animal material and providing an abundant food source for fish. Because caddisflies go through complete metamorphosis, they may be eaten by fish as larvae, pupae, and adults, and are well known to fishermen for just that reason. One of the most famous Northwest caddisflies is the large black and orange October or fall caddisfly.

Many caddisfly families, and even genera and species, are fairly easy to identify. Others, particularly in the case maker families, will take some time to learn and (as with most aquatic invertebrates) can be especially difficult to identify when all you have are early instars. In general, the more straightforward families are separated out first in this section's family key.

Family list:
Apataniidae (apataniid case makers)
Brachycentridae (humpless case makers)
Calamoceratidae (comb-lipped case makers)
Glossosomatidae (saddle- or tortoise-case makers
Goeridae (armored case makers)
Helicopsychidae (snail-case makers)
Hydropsychidae (common net-spinners)
Hydroptilidae (micro caddisflies or purse case makers)
Lepidostomatidae (lepidostomatid case makers)
Leptoceridae (long-horned case makers)
Limnephilidae (northern case makers)
Molannidae (hood-case makers)
Odontoceridae (strong-case makers)
Philopotamidae (finger-net caddisflies)
Phryganeidae (giant case makers)
Polycentropodidae (tube-making caddisflies)
Psychomyiidae (net-tube caddisflies)
Rhyacophilidae (free-living caddisflies, green rock worms)
Rossianidae (rossianid case makers)
Sericostomatidae (bushtailed case makers)
Uenoidae (uenoid case makers)

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