Filth Fly Management in Urban Environments - Urban Insect Pests: Sustainable Management Strategies - page 50

Fly Behaviour (Schoof and Siverly, 1954). This means that

fl y breeding sites can be relatively far from
the locations where the adults become pests.
Most fl ies are, however, not migratory and
will stay within 1-3 km from their breeding
site if food and oviposition sites are available
(Shoukry and Hafez, 1975).
Studies have concluded that fl ies
disperse randomly from their breeding
sites, with no detectable attraction from
long distances. Most fl ies, however, will
follow open areas, landscape features or
fl yways when fl ying from their development
site to areas where they can fi nd food and
breeding sites. During this dispersal, which
is usually upwind, fl ies may follow odour
plumes carried in air currents.
During dispersal, fl ies may be attracted
to light because they are known to be
phototactic. Because these lights are usually
close to places occupied by humans, fl ies
end up gathering close to houses and other
buildings that they can easily enter through
any openings available. Different colour
lights, as well as different colour surfaces,
have different attractive characteristics for
fl y species and can be important in deter-
mining the direction that fl ies will disperse
from a breeding site.

Feeding

Flies vary in their feeding behaviour both as
larvae and adults. Although many of the
fl ies that become pests in urban areas feed
as larvae on decomposing organic matter,
some fl y larvae are specialized in feeding on
high-protein materials, such as meat. Adult
fl ies feed on a liquid or liquefi ed diet that is
sucked into the digestive system. Blood-
feeding fl ies puncture the skin of the host
animal to obtain blood. Flies that do not
survive on blood will feed on a variety of
materials, normally releasing some saliva
on the food item and sucking up a nutritional
liquid. By regurgitating material from
contaminated sources onto clean food fl ies
end up contaminating the food items they
feed on (Sasaki et al ., 2000).

Mating

Mating behaviour varies among the different
fl y species. Normally female fl ies only need
to mate once in order to produce fertile eggs.
Female fl ies will not mate during the fi rst
hours or days after emerging as adults. After
this pre-copulatory period, mating occurs
rapidly on surfaces where males and females
will land. Males are attracted to the females
by pheromones produced by the females.
The pheromone muscalure (Z-9-tricosene)
has been commercially synthesized and
used extensively in fl y traps and bait
products to attract several fl y species
(Hanley et al ., 2004). It is registered for use
in the attraction of house fl ies, stable fl ies,
horse fl ies and eye gnats. Although this
chemical, owing to its low volatility, does
not seem to attract fl ies from a long distance
as a sexual pheromone for other insect
species, muscalure serves as a confi rmation
of the presence of female fl ies.

Medical Importance of Flies

Transmission of pathogens

Filth breeding represents a great threat for
disease transmission to the human popu-
lation throughout the world (Goddard, 2008;
Pehoushek et al ., 2004). Diseases vectored
by different groups of fl ies are among those
causing mortality among civilian popu-
lations and can also be of even greater
importance when armed confl icts occur
(Daniell et al ., 1985; Graczyk et al ., 2001;
Coleman et al ., 2009). Many outbreaks of
disease not normally associated with Diptera
populations are correlated with increases in
fl y populations (Greenberg, 1973) and fl y
control can be associated with declines in
disease prevalence (Echeverria, 1983).
House fl ies have been long suspected as
being involved in disease transmission

Dispersal

Most pest fl ies are strong fl iers and can move
several kilometres at relatively high speeds