Life cycle of silk worms - from worms to cocoons
life cycle of silk worms China - YouTube
Life Cycle Life cycle of silk worms has four stages: such as egg, Larva, Pupa and moth. Domesticated Mulberry silk worms are univoltine, bivoltine and multivoltine. Univoltine silkworm completes one generation, Bivoltine complete two generation and multivoltine silk worm completes 5-6 generations per year. The univoltines lay diapausing eggs and only hatch once in a year at spring season. Bivoltines lay both type of eggsdiapausing eggs and non diapausing eggs which hatch in spring season and autumn season. Multivoltine don’t lay diapausing eggs. Eggs: The size, weight, shapes and color of the eggs varies with the silkworm races, season and nutrition of mother moths at larval stages. Generally the eggs are ovoid, spherical or ellipsoid in shape and flat on one side. The female moth lays Figure 3: Life cycle of Bombyx mori 400-500 eggs on mulberry leaves or artificially prepared butter cups. 100 eggs weigh about 60 mg. the silkworm eggs hibernated during winter will hatch in spring when the mulberry sprouts. Generally the eggs hatch in 9-11 days at proper temperature and humidity condition. Larvae: The larvae are polypodous or eruciform type. The head is hypognathous, heavily chitinized and bright brown in color. There is spinneret, as the median process, at the distal portion of the labial prementum through which silk glands open and silk exudes. It has three pairs of ocelli or simple eyes. The thorax bears 3 pairs of cornical short, jointed true kegs and the prothorax has a pair of spiracles laterally. Abdomen has nine visible segments as the 9th, 10th and 11th segments are fused to form the apparent ninth segment that bears the paired prolegs one in each. The 3rd, 4th, 5th and 6th abdominal segment bears paired prolegs one in each. The dorsum of the 8th segment has a projection called caudal horn. The first eight abdominal segments have a pair of spiracles laterally. The larvae go through four moults and have five instars. The newly hatched worms are black in color and covered with bristles and thus resemble tiny black ants at a glance so called ant worms. The worms are about 3mm long, have 13 segments.