Spider egg chorion sphere size and density

The surface of eggs from 18 species of spiders belonging to 10 families were examined with a scanning electron microscope. The eggs were in one of the following different states: (a) freshly laid; (b) old, unhatched, and desiccated; (c) egg chorions only; and (d) air-dried after alcohol preservation. All eggs had minute spheres covering the outer surface of the chorion. These spheres varied in size, shape, density, and distribution among different species. Most mean sphere sizes and densities were significantly different between spider species. Although the patterns of variation in sphere size and density are not useful for grouping species within families, the two characters may prove to be extremely useful in separating otherwise indistinguishable species of spiders.