Stable fly eggs are white, very similar to house fly eggs and laid in small groups. A female will lay up to 800 eggs, usually in groups of 25–50 after a bloodmeal. Repeated bloodmeals are needed for continued egg production.
Eggs are laid in media that contains a large amount of vegetative matter. Favored habitats for oviposition and larval development are silage, bedding mixed with urine and feces, rotting hay, fermenting feed, piles of grass clippings or other decomposing plant materials.
The larvae of the stable fly are white, cylindrical, tapered anteriorly and very similar to house fly larvae. However, the posterior spiracles differ greatly.
In the stable fly larva the posterior spiracles are roughly triangular, widely separated, and each has three sinuous spiracles set in a thick dark peritreme with the button in the center (Figure 6B). The house fly posterior spiracles are set close together and are nearly D-shaped with a much thinner peritreme than in the stable fly.
The cephalopharyngeal skeleton differs in shape from that of the house fly larva (Figure 7B).
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