Trichoptera (caddisflies)

Order Trichoptera Description

This order of insects are commonly named caddisflies. They are found underwater in cases and often attached to rocks. Trichoptera are most known for their unique characteristic among aquatic insects to spin silk. This silk is used to build shelter, food-collecting nets, and is used to help anchor the insect to the substrate. Most Trichoptera live in and build a case with the exception of Rhyacophilidae, which are free-living, and Hydropsychidae and Philopotamidae, which build nets. Rhyacophilidae are most abundant in lotic, or fast current aquatic habitats. Hydropsychidae and Philopotamidae catch their food as swift currents bring particles of plant material along with the water flow to their nets.


Trichoptera Families:
Click on each below to display information.


BrachycentridaeFamily Brachycentridae

Humpless Case-Maker Caddisfly

Brachycentrid larvae are most frequently found in lotic water systems. They are usually attached to hard surfaces or floating in aquatic moss. These larvae build cases from strips of material that are attached to form a four sided or rounded case. From resting inside the case, Brachcentrid larvae use their middle and hind legs to filter food from the water and substrate in front of them. Larvae are medium in size. The larval body length is 8 to 13 mm. The antennae are held close to the body and there is either one gill present, or there are no gills at all.


Trichoptera Life History
Larvae and Pupae
In general, larvae develop through 5 to 8 instars within a one year period, but some species require 2 years to develop. When larval development is complete, the insect will attach its case to the substrate and seal off the ends. While sealed inside the case, the pupal stage lasts from 2 to 3 weeks.

When the pupa development is complete, the new adult will emerge from the case and swim to the water’s surface. The adult life stage is short; most Trichopteran adults live for less than one month. Adults are primarily active at night. The female will deposit eggs onto the surface of the water in most families, but in some families eggs are laid in dry basins during drought seasons and the eggs will not hatch until water returns.

Feeding Habits
Larval food collection is extremely diverse between genera. Some larvae are mainly predaceous, while others eat only plant materials, including diatoms and algae. Many species use their ability to spin silk to create a food capturing device. Adults from some species feed on plant nectar.

Ecological Importance
Trichoptera are important to aquatic ecosystems because they filter and process organic materials, and they are an important food source in the diet of freshwater fish. These species are also sensitive to pollution, so fluctuations in Tripcoptera populations may reflect changes in local water quality and ecosystem health.

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