The egg is white, elliptical, about 1mm long by 0.26 mm wide, with both ends bluntly rounded and the anterior slightly tapered.

The chorion appears polished, but upon close examination a pattern of hexagonal markings is visible.

On the dorsal side there are two longitudinal curved ridges. Cellular cleavage in the egg begins soon after egg deposition (in about 8 minutes).

Hatching of the larva is through a slit in the dorsal side of the egg.

The slit extends posteriorly as the larva crawls out, anterior end foremost. After the emergence of the larva, the chorion collapses.

Egg Development

The speed with which the larva will hatch from the egg is dependent upon temperature, although most will hatch within 24 hours after egg deposition.

Below 10°C (50°F) and above 42°C (108°F) few, if any, eggs will survive. Optimum temperature for egg survival is about 18°C (64°F). The embryo will not develop in the egg below about 12°C (54°F). There is no hibernation or estivation in the egg stage.

The times required for a first-instar larva to hatch from an egg at different temperatures are typically as follows:

Eggs are deposited by the mated female 4–8 days after copulation. An unmated, virgin female may lay a few eggs, but these will not hatch.

The female selects a suitable oviposition site and deposits her eggs in one to several masses. The number of eggs which will mature in the ovaries at one time is 100–150 (avg.120), and these will be laid over the course of one day if the fly is not disturbed. A female typically deposits 4–6 batches of eggs in her lifetime.