The growth process of silkworms is that the larvae eat mulberry leaves and then spin silk to make cocoons. After forming cocoons, they turn into pupae. After turning into pupae, they break out of the pupa and emerge as moths.
Silkworm is a completely abnormal insect. One generation of silkworm must go through four completely different stages of development: egg, larva, pupa and moth. Under normal feeding conditions, the larvae stage takes 20 to 28 days from hatching and eating mulberry leaves to spinning silk and making cocoons; spinning silk and making cocoons takes about 3 days; and then pupates in 1 to 2 days; the pupal stage lasts 10 to 15 days. The sky turns into a moth, and the moth is the adult insect. On the day when they turn into moths, adult males and females lay eggs one after another. If they lay strong diapause eggs, it will take about 10 days to hatch the next generation of ant silkworms. In this way, it may take 40 to 60 days to complete one generation of silkworms, which will be passed down from generation to generation in a continuous cycle. So, what are the specific shapes of silkworm eggs, larvae, pupae, and adults? How do silkworms in the larval stage grow up little by little? The following is an introduction to the characteristics of silkworm eggs, silkworm pupae, and silkworm moths. Morphology and growth characteristics of silkworms.
Silkworm eggs
Silkworms grow from eggs. Silkworm eggs look like fine-grained sesame seeds, about 1 mm wide and 0.5 mm thick. A female moth can lay 400 to 500 silkworm eggs, 1,700 to 2,000 silkworm eggs, weighing about 1 gram. The color of silkworm eggs is light yellow or yellow when they are just laid. It changes to light red bean color or red bean color after 1 to 2 days, and then changes to gray green or purple after 3 to 4 days, and then no longer changes. , called a fixed color. The outer layer of silkworm eggs is a tough egg shell, and the inner layer is yolk and serous membrane. The embryo in the fertilized egg continues to absorb nutrients during its development, and gradually develops into an ant silkworm. It crawls out of the egg shell and forms when the egg shell is empty. White or light yellow.
Ant silkworm
When silkworms hatch from silkworm eggs, their body color is brown or auburn, they are very small, have many fine hairs, and their shape is a bit like ants, so they are called ant silkworms. The ant silkworm is about 2 mm long and 0.5 mm wide. After crawling out of the egg shell, it will eat mulberry leaves in 2 to 3 hours.
The sleepiness of silkworms
Silkworms eat a lot of mulberry, so they grow very quickly and their body color gradually fades. However, its appetite gradually decreased and even fasted completely. It spit out a little silk, fixed its abdomen and legs on the silkworm seat, raised its head and chest, and stopped moving. It seemed to be asleep, which is called"sleep". The sleeping silkworm appears to be stationary on the surface, but the body is preparing to shed its skin. After shedding the old skin, the silkworm's growth enters a new age, from the ant silkworm to spinning silk and cocooning, a total of 4 molts. . Sleepiness is one of the growth characteristics of silkworms. Sleepiness is a genetic trait of silkworms and is also affected by the environment. The temporarily raised silkworms belong to the four-dormant species.
Silkworm age
Also called instar, it shows that the silkworms are in a certain stage of development. From the ant silkworm to the first molt, it becomes the first instar; after rising from sleep, it enters the second instar; after molting again, it enters the third instar; after the third molt, it enters the fourth instar. The fourth molt is also called the great sleep. After sleeping, they enter the fifth instar. The baby silkworms in the fifth instar grow very fast, with a body length of up to 6 to 7 centimeters, and a body weight that can reach about 10,000 times that of an ant silkworm.
Mature silkworm
When the silkworms reach the end of their fifth instar, they gradually show the characteristics of maturity: first, the eliminated feces change from hard to soft, and from tea-green to leaf-green; the appetite decreases and the amount of mulberry eaten decreases; the front part of the digestive tract is thin and the chest is transparent; After completely stopping eating, the body shrinks, and the abdomen becomes transparent. The silkworm's head and chest are raised, its mouth spins threads, and its body moves left and right to find a place to build a cocoon. Such silkworms are called mature silkworms.
Cocooning
People put cooked silkworms in special containers or on bamboo baskets, and the silkworms will spin silk and form cocoons. Cocooning can be divided into four processes: 1. Mature silkworms first spin out silk and stick it to the cocoon, and then spin the silk to connect with the surrounding cocoon branches to form a cocooning scaffold, that is, a cocoon net. The cocoon net does not have a cocoon shape, but some soft and messy cocoon silk layers that serve as a scaffold for cocooning. 2. After the silkworms form the cocoon net, they continue to spin out chaotic silk circles, thicken the inner layer of the cocoon net, and then spin the silk in an S-shaped manner. The appearance of the cocoon begins to appear, and the cocoon coat is dried. The silk fiber of the cocoon clothing is thin and strong, the display is extremely irregular, and the sericin content is high. 3. After the cocoon coat is produced, the cocoon cavity gradually becomes smaller, and the front and rear ends of the silkworm body bend back to form a "C" shape. The silkworm continues to spin out cocoon silk, and the spinning method changes from an S shape to an ∞ shape, which begins. The process of clearing the cocoon layer. 4. When the body of the silkworm is greatly reduced due to a large amount of silk spinning, the shaking speed of the head and thorax slows down, and there is no certain rhythm. The silk spinning begins to appear chaotic, forming a loose and tender cocoon silk layer, which is called the pupa lining.
Silkworm chrysalis
After the silkworms form cocoons on the cocoons, they will form pupae in 4 days. The body shape of silkworm chrysalis is like a spindle, divided into three segments: head, chest and abdomen. The head is small, with compound eyes and antennae; the chest is equipped with thoracic legs and wings; and the plump abdomen has 9 segments. Professional workers can identify males and females from the lines and brown dots on the abdomen of silkworm chrysalises. When silkworms just pupate, their body color is light yellow, and their pupae are tender and soft.It turns yellow, tan or brown, and the pupa skin becomes hard. After about 12 to 15 days, when the pupal body begins to soften again and the pupal skin becomes a little wrinkled and turns earthy brown, it will form a moth.
Silk moth (adult)
Silkworm moths look like butterflies, covered with white scales, but because their wings are smaller, they have lost the ability to fly. The head of the silk moth is in the shape of a small ball, with bulging compound eyes and antennae; the chest has a pair of thoracic legs and two pairs of wings; the abdomen has no abdominal legs, and the final somites have evolved into external genitalia. The female moth is large and wriggles slowly; the male moth is small and wriggles faster, with its feathers oscillating rapidly in search of a couple. Generally, the female moth can lay fertilized eggs 3 to 4 hours after mating.
Silkworm moths (adults) retain their offspring and will die soon after.
The eggs laid by silk moths → hatching silkworms → turning into pupae → turning into moths will complete the reincarnation of a new generation. This is the life history of silkworms.
The growth process of silkworms is very abnormal.
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