From two to four moults occur, after which the " pronymph " stage is reached, which in the insect is moderately active and possesses wing-rudiments reaching to the second abdominal Segment.
After eating the contents of the egg, the larva moults and becomes a fleshy grub with short legs and with paired spiracles close to the dorsal region, so that, as it floats in and devours the honey, it obtains a supply of air.
There it feeds first as an internal parasite of the waspgrub, then bores its way out, moults and devours the wasp larva from outside.
Growth is accompanied by a succession of moults, the spider emerging from its old skins by means of a fracture which extends along the front and sides of the cephalothorax just beneath the edge of the carapace.
After a series of moults it passes into the second larval stage, somewhat like the parent but differing in having each integumental ring armed with a fringe of backwardly directed short bristles.
Lubbock traced at least twenty moults in Cloeon; at about the tenth rudiments of the wingcases began to appear.
Both agree in having nothing that can be termed a metamorphosis; they are active from the time of their exit from the egg to their death, gradually increasing in size, and undergoing several moults or changes of skin.
After several moults the rudiments of two pairs of wings appear, and then the insect creeps up to the surface of the earth, and on to the vine.
Certain races moult or cast their skin three times during their larval existence, but for the most part the silkworm moults four times - about the sixth, tenth, fifteenth and twenty-third days after hatching.
At successive moults the somites increase in number, new somites being added behind those already differentiated, from a formative zone in front of the telsonic region.