Caddisflies on the Banjo
- Joe Venturo
- Oct 24
- 2 min read
What is it this time?” When we arrive at a new campsite, we never know what surprises await us. After over three-and-a-half years of traveling, we still have not encountered all the surprises one might consider. A few weeks ago, the surprise was a major invasion of caddisflies.
They were everywhere. Apparently they had just emerged from the nearby Snake River in their adult form, and now they were coating the outside walls of our trailer and doing everything they could to get inside to the light. Every time we needed to enter or exit the trailer, we had to race to close the door to let in as few as possible. Even then, there were always a few hanging around inside, and we would have to kill them.
Despite their annoying habits, caddisflies are fascinating. There are over 1,887 species in North America—the seventh largest order of insects. The adult caddisfly lives on land, but the insect undergoes a four-stage life cycle (which means they are “holometabolous”). The female caddisfly lays her eggs near or in freshwater, gluing them in place so that they are not swept away. She can remain submerged for up to 30 minutes by trapping oxygen against tiny hairs that cover her body.
When the eggs hatch, the larval caddisfly develops slowly over multiple stages called “instars.” At one stage, the larva uses silk that it spits out of its mouth to glue debris or small pebbles together, creating a tube-like encasement around its body. Scientists believe that this encasement provides protection and camouflage, but they also suspect that it makes oxygen flow more efficient by channeling the water over the larva’s body. (Here is a site where you can view pictures of various types of caddisfly larvae.)
One individual has experimented with caddisfly larva jewelry. After capturing larvae and removing their natural shells, he puts them in an environment containing only pearls, gems, and flakes of precious metal. The caddisflies create beautiful pieces of artwork out of this material!
The larva’s final instar is the pupa stage, when it fully encloses its tube and later chews its way out as an adult insect. The adults spend their short lives reproducing on land. Interestingly, males may use sounds, unique to each species, to attract females. Caddisflies have different diets according to species. Some are herbivorous, others eat detritus, and a few are predators.
Caddisflies are a reminder that God has given us fascinating gifts to study at every glance. Take the time to notice the little things and learn about everything you can!
Information from:
Awareness: The Official Blog of Alabama Water Watch. "Caddisflies and EPT Friends. https://awwblog.auburn.edu/2023/01/19/caddisflies-and-friends/.
EcoSpark. "Caddisfly Larvae." https://www.ecospark.ca/caddisfly.
Macroinvertebrates.org. "Trichoptera 'Caddisflies.'" https://www.macroinvertebrates.org/taxa-info/trichoptera-larva.
Photo by Joshua Venturo
