Among the Instars: Phryganea

Hello bug folks! Let me introduce you to this little fellow: Phryganea. This is a favorite of mine, as it takes me back to my undergraduate days and some of the first questions that I started asking about aquatic invertebrates. This is a caddisfly larva (Order: Trichoptera), some of the most fascinating critters in our aquatic systems. As adults, they somewhat resemble moths, and the larvae can sometimes resemble caterpillars, in their own way. I always thought the striped face was just too darn cute, but maybe that’s just me being a strange aquatic bug person.

Phryganea, a caddisfly in the family Phryganeidae

What is so fascinating about Phryganea?

First off, caddisflies can spin silk, similar to moths as well. They use this silk underwater for a variety of purposes. The one pictured here would use silk to tie together pieces of plant material from the bottom of a wetland or the edge of a lake and create a case that it lives in. The construction of these cases is one of the most fun aspects of caddisflies. The building materials and construction structures are most interesting and vary from genus to genus; I’ll be focusing in on other families and genera in future posts. Phryganea prefers a plant case, built in a spiral construction that winds around all the way from one end to the other. Species within this genus don’t mind which way the spiral goes, but it must be a continuous spiral.

Phryganea ecology

Typically, organisms in this genus are found in lakes along the margins, where there are plenty of plant materials available for case construction. However, there have been some individuals found as deep as 100 meters in Lake Superior! They are classic omnivores, eating whatever may be easily accessible including algae, aquatic plants, small zooplankton, and aquatic worms. Within the family (Phryganeidae), individuals tend to evacuate their cases if disturbed, much more than in other caddisfly families. Not to worry though! They are much better at finding their original case and re-entering it, so they don’t have to start over and make a whole new home every time.

Taxonomy of Phryganea

Taxonomically, this fellow could be identified to family level in the field with the stark black markings, but requires microscope viewing to determine genus. Be aware though, that some other families can display strong black stripes, so using a dichotomous key is always recommended. It also really helps to have the case included during identification, but since they like to leave their cases during stressful times (e.g. like while being collected), that’s a luxury not always presented. The larval taxonomy isn’t distinguished enough to determine species identifications at the larval level.

Do you find this guy to be cute? Let me know in the comments below or contact me via email! This image will also available for purchase in my shop.

Sources

Wiggins, G.B., 1996. Larvae of the North American caddisfly genera (Trichoptera). University of Toronto Press.