Fly numbers are determined by abiotic factors (environmental factors such as temperature, moisture of breeding habitat and humidity) and biotic factors (natural enemies including parasites, predators and pathogens).
Theoretically, a house fly population would grow to astronomical numbers if there were no factors limiting production. However, the abiotic and biotic factors prevent this from happening.
Fly populations can reach unacceptably high levels in and around confined animal production facilities when the livestock management system includes practices which cancel out the abiotic and biotic factors.
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