Adults are 6–7mm long; females are larger and have a wider gap between their eyes compared to males. They have red eyes and sponging mouthparts. The thorax has four narrow black longitudinal stripes. The abdomen is grey or yellowish with a dark midline and irregular dark markings on the sides. The underside of males is yellowish. 

Eggs are white and about 1.2 mm in length. They are laid singly but are piled in groups. Each female can lay about 500 eggs in several batches of 75 to 150 eggs in 3-4 days. 

Larvae or maggots are 3–9 mm long in early instar, cream to white in colour, and cylindrical but tapering toward the head. Maggots go through three instars and a full-grown maggot is 7–12 mm long. 

Pupae are about 8 mm long, bluntly rounded at both ends, and the colour ranges from yellow, red, to black as the pupa ages. It takes two to six days for the adult house fly to emerge. 

Life Cycle

7 to 10 days in warm temperatures, and up to two months in suboptimal conditions.

Generations per year

10–12 in temperate regions, more than 20 in tropical and subtropical regions.