1971 School Magazine

After twenty days as a silkworm pupa the moth emerges from the cocoon breaking tde threads as it emerges, for which reason cocooni are stifled in ali factories. The moth is white and although the silkworms grow up to three and a half incf,es the moth ls about one and quarter inches long. For some unknown reason the male moths emerge before the female moths in most cases and it wis several days before we had a female moth emerge. All our moths emerged at night and their wings"dried before.morning. Of the silkworms we hadlo help from their cocoons all had crumpled wings. This must be a result of not being able io sp.eud them soon after hatching. The female moth differed from the male in several ways and was therefore easy to pick out. She was larger than the male moth and whiter in colour, the males tending to be more beige. The male moths were constantly on the move in the tirst week where the female moth on the whole was motionless- The moths mated for times ranging from several minutes to several horrrs. All our molhJhid their eggs quite well except for one female moth who coJld only lay one every twenty minutes or so. She had mated several times so we assumed that all her eggs were fertilized. We decided that when she died iie yogld, remo.ve the eggs from her abdomen. Her legs started TgvTg-: We could not sew her up again so we let her die. When we removed her eggs a"nd placed them in the box we observed them. O-ul efforts were all^in vain, the eggs did not go black as they were unFertilized. She must have had a blockage'in her vagina. Our moths all laid at different times and at one stage we had a picture in yellow, reddish brown and grey e€gs on the paper. The eggs when laid are yellow and after two days go reddish 6rown; a f'ew days later they. turn grey. Although a female is usually inactive she does flap her wings when she is laying hei eggs. Silkworms are very hardy insects. This year we had ants in the box where the silkworms are kept. It was several hours before we noticed them. In iti, tlme they had managed to drag one silkworm out of the box and.kill.it. They had-also eaten all the legs off one moth and three of the legs off another. The moth which was missing all its-legs and also we had discovered later a hole in its side-, lived for almost two days. The moth which had lost tiree legs lived as long as most of the moths, as did a few oth6rs which werE missing one leg. Several moths also lost feelers but managed to survive without them. One lost a feeler when it was being removed from its cocoon and the moth with all its legs eaten had both feelers off. . The moths came out of the cocoons two weeks before one died. In this time none had eaten anything and the male moths had been .consistantly rjn th6 move. When the first moth died we dissecied it. It was a female and inside there was a small pinkish sticky section which was the ovary and a very small hard white gland which produced it r.gg, *r'ttint. Apart from these the body cavity was completely

empty. We are not certain whether this is the way the moth emerges from the cocoon or whether ali the internal-organs were used up for source, ofLrr".gy., the.moth progressed througir its foodless duyr. Wir*n tn the silkworm the mouthparts had been fairly large in comparison to the head, in the moth the mouth was barely visitrle. Both the moth and the silkworm possessed compound eyes but the moth's eyes seemed larger and duller than the silkworm's. the s1$ produced from home raisers is practically useless. If the moths emerge it is useless ind stifled cocoons are no use unless they are in large quantities as it takes one thousand, six hundied'to two thousand cocoons to produce one pound ofraw silk. Most home grown silk is made into bookmarks or collects dust as most people do not know what to do withit. The leaves of the mulberry tree are of two types of mulberry. The white mulberry and the- black mulberry are the ones on which silkworns are commonly raised. Most Australian trees are of the black mulberry type but silkworms raised in factories are brought up on white mulberries. The silkworm will also live on lettuce leaves, strawberry leaves and beetroot leaves but the best cocoon is made with a diet of mulberry leaves. Silkworms can be raised most of their life on many types of leaves as long as they receive mulberry leaves for the last few vital ,iueeks. - The white mulberry is raised for silkworms for several reasons. One is because its leafs early and also b.ecause the_ total weight of leaves produced is greater than the black mulberry. The leives of the white mulberry have a greater nutritive value and therefore the total amount of leaf needed is less than the black type. Silkworms fed on the black varietv tend to prodnce coarser silk also necessitating a gteater weight of leaf. _ The leaves of the black variety are larse heart shaped and hairy on the underside where as tfie white mulberry leaves are a clear, beautiful green and quite smooth. ' .The ^cocoons produced- by both varieties range in colour from white to saffron yellow. Cocoons'have also known to be pink and gr-een depend.ing on the diet of leaves- The leaf is composed of several different types of matter. The solid matter and water in the leaf pass through the silkworm without nourishing it. The saccharine matter nourishes the silkworm ind forms its animal matter where as the resinous matter in the leaf accumulates, clarifies itself and fills the silk saes. These are long twisted sacs which lie partly beside and partly underneath the stomach of the silkworm. Each sac has.an olening on the lower lip or labium of the worm. The silk is a viscous fibrous protein which hardens on contact with the air. fhe chemical structure of silk is very similar to nylon.

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