Cluster Flies
Often confused with the common house
fly, cluster flies are
roughly the same size. Some characteristics that differentiate the cluster
fly:
they fly somewhat more slowly than the house fly, they almost always fly toward
windows on the warm side of a structure and their wings overlap almost completely,
when at rest.
Cluster flies breed in the ground outside of buildings during the
warm weather (late Spring into early Summer) using earthworms as a food source for the immature larva (maggots).
The flies later pupate (go into the cocoon stage), then hatch as adult flies.
In temperate areas, often
in late August, these flies begins to migrate indoors finding any small cracks or crevices
that permit entry into structures. These may include areas around window frames, door frames
or eaves. Entry tends to be on the same, warm, sunny side (often the
southern or western exposure) of the structure as the flies later emerge from.
During the Fall, Winter or Spring months, these flies
may emerge, particularly on warm, sunny days. The flies appear at windows
buzzing and "clustering" around those areas to the dismay of the occupants.
This fly can become a problem in virtually any structure and they have, on occasion,
been a
problem in sensitive areas such as hospitals, where they are especially unwelcome.
Control
Stop them on the Outside
One of the best ways to minimize entry of this pest is
by applying a repellent, residual insecticide within a week or two of the time when these
insects are known to begin migrating indoors. Within the US,
Cooperative Extension
is a
good source to check with for timing information for your immediate region.
These residual insecticides are applied outdoors to window frames, door frames, soffits
and eaves as well as any other areas that are vulnerable to entry.
Some have suggested that application to
the surrounding soil may also help minimize cluster fly populations and later
entry, but others caution that since flies may come from other, adjacent areas,
treating the soil is a futile attempt to control the problem.
Because some of the treatment areas are many feet off the ground,
an application may require power equipment. Calling in a professional,
commercial applicator to do the application for your may be best. Product used by commercial
applicators (common name in parentheses) include Prelude or Dragnet (permethrin), Demon
or Cynoff (cypermethrin)
and Demand CS (lambda-cyhalothrin).
Inside
For existing infestations indoors, insecticides may be
used selectively to control this pest. A total release fogger such as Pro Control Plus may be used
in an attic or other room to control flies that may have migrated in.
We also offer an aerosol
boric acid dust product, Borid Turbo. This product,
which applies as an aerosol but dries into a dust, may be injected
into wall voids around window frames and door frames with the provided void
injector. A 1/8" hole may be drilled every 16 inches on center around the
frame areas for this application. A small dab of caulking will seal the openings
afterward.
In some cases, the use of electronic fly traps (light
bulbs with a "stun" unit that disables the flies causing it to fall
into a glue trap) in attics and drop ceilings have been helpful. These do
require electricity and maintenance, things not always available in the vacation homes affected by these flies.
Another solution is Cluster
Buster, a cluster fly trap. These traps attach to the inside of
any window. The white plastic traps are filled with finely ground
(powdered) egg
shell. A large cutout on the top of the trap provides an "exit" which attracts the flies into the trap. Once inside, they encounter
the powder which is
so light and fluffy that the flies actually sink into the powder, providing a
"quicksand" effect. The powdered egg shell clogs the sphaeracles,
a component of their respiratory system. These traps represent the most
conservative approach to control and are virtually non toxic. These non
refillable traps
require no energy to operate and each hold up to 1000 flies or
more.
We have sold the traps for several
years now and have had excellent feedback from customers. The manufacturer
guarantees the traps to work for cluster flies. They also recently
introduced a LadyBug
Buster traps which looks similar and will help with
invading ladybugs.
Please contact us
If you have any other questions regarding
cluster flies or
any other pest problem, please write to us by clicking
here or call us toll free at 800-433-1128 or locally at 845-356-2837
weekdays between 8 am and 4 pm ET. You may reach us by fax at 845-356-2836.
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