Silkworm Eggs

the eggs of the moth of silkworms, from which come the caterpillars whose pupal stage is passed in silk cocoons. The eggs begin to form in the ovary of the caterpillar, then complete their development in the larva. The eggs of the Chinese silkworm have an oval, somewhat flattened form. They are covered with an elastic semitransparent shell with an opening at the tip (for spermatozoa penetration) and with many air-carrying canals for the embryo to breathe. Some silkworm types have eggshells covered with a sticky substance (“sticky” and “loose” silkworm eggs). The dimensions and weight of the eggs depend on the type, the nourishment of the female moths, and the laying periods. The average weight of the Chinese silkworm egg is 0.5–0.7 mg; the average clutch weighs 280–380 mg and consists of 500600 eggs. There are 1,500–2,000 eggs contained in 1 g. The oak silkworm lays larger eggs: 1 g has but 120 eggs. The Chinese silkworm hibernates in the egg stage, coming to life in the spring. In the bivoltine types every second generation of silkworm eggs does not hibernate.