Nuisance Aquatic Insects, Caddisflies, Stoneflies, and Mayflies
The adults of several types of aquatic insects will
frequently emerge in large numbers, causing concern among
homeowners. Three types of aquatic insects frequently
encountered around homes are caddisflies (Trichoptera),
stoneflies (Plecoptera) and mayflies (Ephemeroptera).
Caddisflies are distinct from the other two groups by
the hair-covered wings which are held roof-like over the
back when at rest. Mayflies have large forewings, small
hindwings that are held together at rest over the body.
There are also 2 (rarely 3) caudal filaments which are
equal to or greater than the length of the body.
Stoneflies have a hindwing which is larger than the
forewing, and the wings are held flat over the back.
There are two caudal filaments, but they are generally
shorter (less than half the length of the body).
The adults of these insects are generally short lived,
especially in the case of the mayflies, and they
generally do not feed. Even though homes near aquatic
habitats may be covered with resting insects during mass
emergences, expensive chemical controls are seldom
necessary.
The insects can be allowed to disperse naturally, or
they can be removed by sweeping or vacuuming. Those
insects which get indoors can be subdued with an aerosol
flying insect spray containing pyrethrin, and then
removed. An ordinary aerosol hair spray will also subdue
flying insects by stiffening their wings and allowing
their removal.
These aquatic insects are attracted to lights, and
when they are active it may be necessary to reduce
outside lighting or switch to yellow light bulbs. These
insects are least responsive to the yellow light.
For a complete listing of suggested control options
for all home, yard and garden insect pests contact your
local Extension Service, found under local government in
the phone book.
Read and follow instructions on the pesticide label.
Heed all warnings. Check with your physician if you have
any concerns regarding your personal health risk.
Tom Ellis, M.S., Department of Entomology.