Though house flies breed and feed prolifically in warm temperatures, when the mercury drops, they become inactive and die. This means that during the summer, the eggs hatch and the young mature at their fastest rates, but during winter, colder temperatures kill off most of the outdoor-dwelling insects. The ones who survive are those living in warmer climates or who take refuge indoors.
Maturation, Life and Death
Temperature affects not only the survival of house flies, but the rate at which they mature. When the temperature nears 99 degrees Fahrenheit, a house fly's eggs can hatch in less than eight hours -- if the temperature is lowered to 59 degrees, it can take two days. As the young develop, they're still affected by temperature. Under optimal conditions, they can mature into adults in as little as four days, but in cooler temperatures, it can take up to 30. Adult house flies are affected by temperature as much as their young, becoming inactive when temperatures fall below 45 degrees and dying when they fall below 32. Because house flies thrive in hot environments and die off in colder ones, they are generally a summertime pest, rather than an autumn or winter one.
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