Facts, Identification & Control

Latin Name

Order Trichoptera


Caddisfly is a generic name given to the insects that belong to the Order Trichoptera. There are approximately 1,200 U.S. species within this order, and some entomologists study caddisflies exclusively. The caddisfly is known by many names, including sedge, shadfly and periwinkle. Caddisflies belong to one of the most prolific orders in the animal kingdom.

Caddisflies are not actually flies. Flies belong to the order Diptera. Caddisflies belong to the order Trichoptera.  Adult caddisflies are terrestrial, while larvae are aquatic and can be found in lakes, rivers, streams and other freshwater sources. Caddisflies form a very significant part of freshwater food chains, and the presence of these insects typically indicates that an aquatic ecosystem is healthy.

Adult caddisflies are similar in appearance to moths. They have minimized mouthparts and well-developed compound eyes. Although they live on land, adult caddisflies typically inhabit areas near freshwater sources in order to ease breeding processes.

Behavior, Diet & Habits

Caddisfly larvae are aquatic, while adults are terrestrial and visit water only to lay their eggs. Caddisflies serve an important role in upholding the ecological balance of freshwater sources, as fish feed on them. Caddisflies also help keep these bodies of water clean by feeding on fallen leaves and other detritus. Spiders and other insect predators, such as birds, may eat the adults. Caddisflies serve as a possible food source for a whole host of animals.

Caddisflies make shells or casings for their pupal stage. The type of materials used for caddisfly casings varies from species to species. Some use soil for casings, while other caddisflies use dead twigs and leaves.

Caddis vs Fly (diptera)
Contrary to popular belief, caddis flies do not belong to the order Diptera, so they are not flies. They are part of the order Trichoptera. While the Diptera group, including the fruit flies (Drosophila spp.), contains over 18,000 species in the United States and Canada, there are approximately 1,200 types of caddisflies in North America alone.

Flies from the Diptera order have only one pair of wings, while caddisflies have two pair of wings. Many flies lay their eggs in decaying or fermenting material. When fly eggs hatch, the larvae eat the decaying material where they hatch. However, caddisfly larvae feed on detritus material from the bottom of lakes or rivers. This is because caddisflies lay their eggs on the surface of bodies of water.

caddisfly image


Like many other insects, the complete life cycle of the caddisfly is comprised of four stages: egg, larval, pupal and adult. After mating, the female caddisfly skims the surface of a water source and deposits her eggs in strand-like formations. These eggs are a bright green in color and sink to the bottom.

Eggs eventually hatch into caddisfly larvae. Caddisfly larvae are grub-like in appearance and feed on detritus within the bodies of water they inhabit. Caddisfly larvae create strands of silk from their salivary glands. After feeding, caddisfly larvae begin to form casings used in the pupal stage. These cases are constructed of small rocks, twigs and other gathered materials.

Signs of a Caddisfly Infestation

Homeowners typically encounter only the adult stage of caddisflies. They may be seen gathering near lights, sometimes in large numbers, but are incapable of breeding and infesting indoors.

How Orkin treats for caddis flies

Caddis flies are an aquatic insect that develop in streams and other bodies of water spending most of their life as immatures they are an essential source of food for fish.

As adults, they may swarm in large numbers and are very attracted to lights. It is this swarming behavior that makes them pests, plus the reported occurrences of allergic reactions and asthma that are associated with their presence.

The best approach to treating caddis flies is to be patient since they do not live more than a few days after becoming flying adults. If putting up with the swarm is not possible, using a heavy-duty vacuum or applying registered and appropriately labeled chemical insecticide will help reduce the problem by quickly knocking down the population.

Non-chemical approaches to treatment involve light management. Some successful practices include:

  • Replacing standard incandescent and fluorescent lights with sodium vapor lights that are less attractive to insects.
  • Installing lights away from buildings, if possible.
  • Turning lights off when adult caddisflies are flying.