Fabre has found that in the nests of some species of Osmia the young bee developed in the first-formed cell, if (as often happens) she emerges from her cocoon before the inmates of the later cells, will try to work her way round these or to bite a lateral hole through the bramble shoot; should she fail to do this, she will wait for the emergence of her sisters and not make her escape at the price of injury to them.
The thread so ejected forms the silk of commerce, which as wound in the cocoon consists of filaments seriposited from two separate glands (discovered by an Italian naturalist named Filippi) containing a glutinous or resinous secretion which serves a double purpose, viz.
It also uses the burrow as a safe retreat during moulting and guards its cocoon and young in its depths.
As a rule terrestrial spiders guard the cocoon in the permanent burrow, as in the trap-door spiders, or in the silken retreat which acts as a temporary nursery, as in the Salticidae.
The worm itself, after the cocoon has been used, is eaten and is esteemed a delicacy.
When the larva is fully mature, and ready to change into the pupa condition, it proceeds to spin its cocoon, in which operation it ejects from both glands simultaneously a continuous and reelable thread of 800 FIG.
SILK, a fibrous substance produced by many insects, principally in the form of a cocoon or covering within which the creatures are enclosed and protected during the period of their principal transformations.
- Cocoon of Silk of Bombyx mori.
- Chinese Tussur Moth, yearly and producing a soft flossy cocoon; the Chinese monthly worm, B.
In this way it is believed that the sub-aqueous cocoon in which the pupal stage is passed becomes filled with air.
Other species of wandering habits carry the cocoon about with them, sometimes attached to the spinnerets, as in the Lycosidae, sometimes tucked under the thorax, as in the large tropical house-spider, Heteropoda regia, one of the Clubionidae.
From two to three weeks after the completion of the cocoon the enclosed insect is ready to escape; it moistens one end of its self-made prison, thereby enabling itself to push aside the fibres and make an opening by which the perfect moth comes forth.
The lower the temperature at which the worms are maintained the slower is their growth and development; but their health and vigour are increased, and the cocoon they spin is proportionately bigger.
In this connexion he established the very important practical conclusion that worms which contract the disease during their own life-cycle retain sufficient vitality to feed, develop and spin their cocoon, although the next generation is invariably infected and shows the disease in its most virulent and fatal form.
If the attack comes on a short time before maturity, the worms are able to spin a cocoon of a feeble character, but worms with this disease never change into chrysalides, but always die in the cocoon before transformation can take place.
(2) The outside layers of the true cocoon are too coarse and uneven for reeling; and as the worm completes its task of spinning, the thread becomes finer and weaker, so both the extreme outside and inside layers are put aside as waste.
(4) During the process of reeling from the cocoon the silk often breaks; and both in finding a true and [[Table Iv]].-Silk Goods exported from the United Kingdom.
When the waste contains any large percentage of worm or chrysalis, it is taken to a " cocoon beater," a machine which has a large revolving disk on which the silk is put, and while revolving slowly is beaten by a leather whip or flail, which loosens the silk and knocks out the wormy matter.
It has important ironworks, foundries, locomotive works and silk manufactures, as well as sugar factories, printing works and cocoon-raising establishments.
The young leave the cocoon as fully formed earthworms in which, however, the genitalia are not fully developed.
He had risen to fear, heartache, anxiety, bliss, pain and a hundred other feelings that made you beg to be able to bury your head beneath the covers and stay in the warm cocoon of sleep forever.
Many of the Hydrophilidae construct, for the protection of their eggs, a cocoon formed of a silky material derived from glands opening at the tip of the abdomen.
The second step in the evolution of spinning instincts was probably the making of a silken chamber for the reception of the cocoon itself and for the protection of the mother while guarding it and her newly-hatched young.
If an aperture for ingress and egress, for purposes of feeding, were left in the wall of such a chamber, there would arise in a rudimentary form what is known as the tubular nest or web; and the next important step was possibly the adoption of such a nest as a permanent abode for the spider., Some spiders, like the Drassidae and Salticidae, have not advanced beyond this stage in architectural industry; but next to the cocoon this simple tubular retreat - whether spun in a crevice or burrow or simply attached to the lower side of a stone - is the most constant feature to be observed in the spinning habits of spiders.
It is in this and related families that the greatest diversity in the colour and form of the cocoon is found.
In these spiders, too, the newly-hatched young shift for themselves as soon as they emerge from the cocoon; in others that guard the cocoon the young stay for a longer or shorter time under their mother's protection, those of the wandering Lycosidae climbing on her back to be carried about with her wherever she goes.
The young emerge from the cocoon in the early spring, grow through the summer, and reach maturity in the early autumn.
- a, Pear Saw-fly (Eriocampoides limacina); b, larva without, and c, with its slimy protective coat; e, cocoon; f, larva before pupation; g, pupa, magnified 4 times; d, leaves with larvae, natural size.
The whole cocoon with its enclosed pupa weighs from 15 grains for the smaller races to about 50 grains for FIG.
Cf seed of 30 grammes producing 30,000 to 35,000 silkworms (30,000 may be depended upon to reach the cocoon stage) will give a harvest of 130 to 140 lb fresh cocoons and an ultimate yield of about 12 lb raw silk properly reeled.
Sinensis, having several generations, and making a small cocoon; and the Madrasi worm of Bengal croesi), the Dassee or Desi worm of Bengal (B.
Abandoning the long and somewhat heavy magnetic needles that had been used up to that date in galvanometers, he attached to the back of a very small mirror made of microscopic glass a fragment of magnetized watch-spring, and suspended the mirror and needle by means of a cocoon fibre in the centre of a coil of insulated wire.
In April a single worm got oak-buds, on which it throve, and ultimately spun a cocoon whence a female moth issued, from which Guerin Meneville named and described the species.
About one-sixth of this weight is pure cocoon, and of that one-half is obtainable as reeled silk, the remainder consisting of surface floss or blaze and of hard gummy husk.
As the outer flossy threads and the inner vests are not reelable, it is difficult to estimate the total length of thread produced by the silkworm, but the portion reeled varies in length and thickness, according to the condition and robustness of the cocoon, in some breeds giving a result as low as Soo metres, and in others 900 to 1200 metres.
Sir Thomas Wardle of Leek, in his handbook on silk published in 1887, showed by a series of measurements that the diameter of a single cocoon thread or bave varied from o oth to -nth part of an inch in diameter in the various species of Bombycides, whilst those of the Saturnides or wild species varied from - 0 oth to 3-0 0 th part of an inch.
- Cocoon of Antheraea pernyi.
- Cocoon of Antheraea mylitta.
In the most approved modern filatures there is a separate cocoon boiler (cuiseuse), an oblong tank containing water boiled by steam heat.
This increased production of medium silk, and the growing demand for fine sorts, induced many of the cocoon-growers in the Levant to sell their cocoons to Europeans, who reeled them in Italian fashion under the name of " Patent Brutia," thus producing a very fine valuable silk.
The pupae in most of these pests are found in an earthen cocoon beneath the ground, or in some cases above ground (Lophyrus pini).