Filth Fly Management in Urban Environments - Urban Insect Pests: Sustainable Management Strategies - page 58

window screens. Small holes such as these
should not allow other pests to enter.
Traps can be baited with fermenting
molasses, ammonium carbonate, phero-
mones, commercial mixtures and other
attractants but many of these materials
should be restricted to outdoor use due to
the obnoxious odours, especially after large
number of fl ies are captured, die and start to
decompose inside the trap. Even outdoors,
it is recommended that fl y traps be emptied
routinely to avoid strong odours from the
rotting mess of fl y bodies.
For indoor use, sticky paper (fl y paper)
and electrocution traps are better choices
because they do not emit obnoxious odours.
These traps are effi cient in reducing the
populations of fl ies within enclosed areas
but should not be used outdoors because of
the lack of selectivity, causing the death of
large numbers of non-target and benefi cial
insects and other organisms without effect-
ively lowering the levels of pest fl ies.

food preparation areas. The application of
residual insecticides to natural-fi bre cords
(Hertz et al. , 2011) can also serve as an
effi cient way to eliminate fl ies taking
advantage of the fl ies' natural behaviour.
Insecticide application either outside or
inside structures mostly provides temporary
control, so it is important to invest time and
effort in locating potential breeding sites
and applying other preventive measures as
discussed elsewhere in this chapter. Care
should be taken to prevent the elimination
of natural enemies and other natural control
elements that can be helpful in controlling
the pest fl y populations. Chemical pesti-
cides can eliminate natural enemies of fl y
pests so use of these chemicals can some-
times result in resurgence of the pest fl y
populations, sometimes to higher popu-
lation levels than originally observed.

Residual sprays

When other methods fail to provide
adequate fl y reduction, applying a residual
insecticide spray to outdoor surfaces to
control adult fl ies is generally recommended.
Residual sprays can be applied to overhead
structures such as leaves, beams, wires, and
ceilings of porches, patios, carports, garages,
breezeways, etc. where house fl ies rest
during the night in warm weather. The
resting fl ies will be killed by prolonged
contact with the insecticide.
Barrier sprays applied to fl y landing
areas (structural walls, landscape plants,
etc.) on outside structures can be used to
knock down populations quickly but long-
term methods need to be used for a more
durable effect, especially when weather
conditions cause rapid washing off or
degradation of residual applications.
Because fl ies do enter structures through
cracks and crevices in the walls or around
windows and doors, the application of
residual pesticides on these locations forces
contact between the fl ies and pesticide-
treated surfaces as the insects enter the
structure.
In areas around packing houses and food
processing plants, where large volumes of
culled produce or food wastes attract high

Insecticide treatments

Chemicals are the best option for fl y control
in many situations, both indoors and out-
doors. Gradual increases in label restrictions
prevent many older products from being
used in outdoors applications and this
situation is likely to persist in the future.
Also, as a result of their generally high
reproductive rate, pest fl y populations can
easily counteract many control methods
and develop resistance to active ingredients
within a very short period of time. The use
of an integrated approach to fl y control
using chemicals, with an alternation
between different classes of pesticides, is an
important factor in preventing development
of pesticide-resistant populations (Bloom-
camp et al. , 1987).
If large numbers of adult fl ies are present
inside a building, a quick-acting, short-
residual aerosolized insecticide can be used
for rapid knockdown, as long as the
insecticide is labelled for the location where
it will be used. Mist applications in tightly
closed rooms will generally work best but
care should be taken to avoid contamination
of food, air and other items, especially in