The larva then works at its cocoon, which consists at first of a sack of pure, perfectly white silk, an extremely delicate sack, affording little protection to the recluse. This is only a woof, destined to become a better stuff, not by additional weaving, but by the application of a special lacquer. The spinner is a worker in oiled silk. In the spinning-mills of the carnivorous Wasps, two methods of manufacture are employed to give the silken fabric greater toughness. On the one hand, the fabric is encrusted with numerous grains of sand, which produces an almost mineral shell wherein the silk has no other function than to serve as a cement for the stony materials. That is how the Bembeces, the Stizi, the Tachytes and the Palari work. On the other hand, the larva elaborates in its stomach, in its chylific ventricle, a liquid varnish which it disgorges into the meshes of a rudimentary tissue of silk. Directly it trickles into the web, the varnish hardens and becomes a lacquer of exquisite daintiness. The larva next ejects at the base of the cocoon, in the form of a hard stercoral plug, the residue of the chemical process accomplished in its stomach for the elaboration of the varnish. This method is that of the Spheges, the Ammophilæ and the Scoliæ, who varnish the inner wrapper of their multiple cocoons; and of the Crabro-wasps, the Cerceres and the Philanthi, [43] whose delicate cocoon consists of only a single thickness. The Pelopæus adopts this last procedure. When finished, her work is an amber-yellow fabric suggesting the outer skin of an onion in fineness, colour, transparency and the rustling sound which it emits when fingered. Relatively long in comparison with its width, as is demanded by the capacity of the cell and the slender form of the future insect, the cocoon is rounded at the top and suddenly truncated at the base, which is rendered hard and opaque by the stercoral plug, the by-product of the lacquer-factory.