Strand of Silk, A

e silk comes from fibers of cocoons webs and nests spun by spiders caterpillars and insects for their protection here is a garden spider and her silken web this is her nest of pure silk the work of many hours most of the silk that we use comes from cocoons of Mulberry silk moths silk moth eggs are about the same size as the head of a common pin when brought into the light and fresh air at room temperature they hatch in about 10 days the baby caterpillar is dark brown in color he has six legs on his thorax and eight false legs behind the abdomen many spines cover his body they protect him from being eaten by birds in this enlarged picture you can see these spines which he will lose after his first mol molting is shedding his skin in he will mold four times during his short life the leaf of the mulberry tree is the caterpillar's only food here the children are gathering leaves from a teas weeping mulberry tree this tree does not grow very tall and is often used for beautifying Parkways here is another kind of mulberry tree which grows very tall this Leaf is from a te's weeping mulberry tree note that it is small long and narrow these large leaves are from the tall mulberry tree they contain less juice than the small variety but appear much earlier in the spring as the time comes for the hatching of the silk moth eggs During the period of growth the caterpillars show no desire to wander off or Escape caterpillars will not search for food so unless fed fresh food regularly they will either die or fail to reach a healthy maturity the result will be very small cocoons of broken threads a number of caterpillars eating together sound like Falling Rain listen here are two half grown caterpillars one is cream colored and the other has rings or is banded which indicates a different species caterpillars eat greedily and require a constant supply of fresh clean leaves they etch little semicircles from the edges of the mulbery leaves with their sharp jaws and will eat their weight in leaves daily except for the short periods required for molding this continuous eating lasts until they have reached their full growth they Thrive better on the Small Juicy leaves which contain more cedin a substance in the juice of the leaves the quality of silk depends upon the amount of cedin in the leaves the more cedin the finer the thread after eating from 30 to 40 days the healthy caterpillar grows to an average length of 2 and 1/2 in though this caterpillar is of average size he stretches himself to almost 3 in in length these caterpillar Engineers are preparing to anchor the threads which will hold the cocoons that they are about to spin each caterpillar makes a framework by stretching a few strands of silk between various points after making a loose Network upon the supporting strands they begin to spin the silk of the Cocoon the structure of the network is so thorough that some effort is required to remove their completed homes the caterpillar has two silk glands one on each side of his body when these are completely filled he stops eating and is ready to spin his silk as spinning begins he expels fluid from each of his small glands to a tongue likee depositor on his upper lip this fluid upon contact with the air forms a single filament or a strand of silk he moves his head backward and forward producing a patch made up of many silk and figure 8s the Cocoon grows in thickness as hundreds of these patches are spun The Unbroken strand of the completed cocoon is about 3/4 of a mile long in this ordinary shoe box interlaced with sticks to form small squares or cubicles these caterpillars have selected places for spinning their cocoons more than 150 caterpillars have spun their homes in this box the banded in the cream colored caterpillars spin either a gold or a white cocoon the cocoons are usually gathered after the fifth day of spinning these girls are removing the coarse covering of network of structural fiber which anchors the cocoons unless it is completely removed the end of the thread for unwinding cannot be found almost 2 weeks after spinning is completed the caterpillars change into moths inside the cocoons they moisten one end of the Cocoon push aside the fibers breaking the threads and emerge with eyes Wings six legs two feathery antenna but no Jaws the cocoons from which they emerge are worthless since many strands have been broken the moths are ash white in color and have short Wings the male has a thin body and is about 1/2 in Long this picture shows his small body the female is somewhat longer and much stouter few silk Ms can fly and none eat as they have no Jaws seldom do they live longer than 10 days after emerging from their cocoons from 4 to 6 days following their mating the female lays an average of 300 eggs in a single layer at first the eggs are bright yellow in a few days all that are fertile changeed to shades of tan brown and dark slate non-fertile eggs turn white or a light gray color cocoons which are to be Unwound are usually treated with steam or placed in a hot oven to kill caterpillars inside this treatment prevents The Moth from coming out the cocoons are then placed in hot water to soften the gummy substance holding the threads together this boy is finding the end of the thread by carefully pulling several fibers from on the end of a softened cocoon after unraveling a small amount he proceeds to wind the thread upon a pencil unwinding must be done slowly and smoothly to prevent breaking the thread it is important to remember that the water must be kept hot during the entire period of unwinding e this girl is preparing to wind the silk of her cocoon upon a homemade reel or spool the end of the finger over which the thread passes must always be kept moist to avoid friction which might cause the thread to break the thread is removed as a skce of silk five of these fibers are combined to form the silk thread which is woven into cloth yet unmatched in quality and Beauty by modern substitutes often it is woven into a colorful ribbon to decorate the lovely hair of a child or it may also become an attractive scarf which will enhance the natural beauty of our young ladies there are countless other commercial uses for [Applause] silk