Caddisflies

APPEARANCE & IDENTIFICATION

Caddisfly adults are long, slender, and vary from about ¼ – 1 inch long. They have two pairs of wings that are held “roof-like” over their body when at rest. Their antennae are as long or almost as long as their entire body.

BEHAVIOR (ACTIVITY)

Caddisflies spend their egg and larval stages in water. The larvae construct a larval case and become pupae while still living inside the case.  They leave their aquatic environment as adults and are attracted to lights.

DIET

Caddisflies feed on decaying aquatic plant debris and algae as immatures. In addition, some species are predacious on other aquatic organisms. Adults do not feed, and their primary purpose is mating and laying eggs by the females.

HABITAT

The principal habitats of caddisflies are streams, ponds, and lakes.

REPRODUCTION & LIFECYCLE

Caddisflies complete four developmental stages – egg, larva, pupa and adult. The larval stage lasts 1-2 years; the pupal stage lasts about 2-3 weeks; and adults emerge from their water habitat and fly away in large swarms. Adults live less than 30 days, but before they die, they mate and the adult female lays her eggs in or near the water.

SIGNS OF THEIR PRESENCE (COULD BE DAMAGE)

The most obvious signs of caddisflies are adults swarming from their aquatic habitats and showing up around sources of light at night. Caddisfly adults become a pest problem when they enter homes and land on walls and other surfaces. At times, the number of adults in a swarm can be huge.

PREVENTION TIPS

Preventing caddisflies involves nighttime light management and exclusion via screening and keeping doors and windows closed. Prevention may include:

  • Using sodium vapor lights instead of incandescent and fluorescent lights.
  • As long as security and safety aren’t compromised, placing lights as far away from buildings as possible.
  • Extinguishing lights and keeping doors and windows closed when adult caddisflies are active.

HOW TO CONTROL

If caddisfly control is necessary, the use of heavy-duty vacuums to physically remove adults, or applying registered, permissible chemical insecticide will help reduce the problem by quickly knocking down the population of adult caddisflies. Applying insecticides to aquatic habitats is generally not effective and may cause environmental damage to streams or other bodies of water. Remember to always use any product in strict accordance with the label.