Note 13 — Chapter IV · THE AGENIÆ; THE PELOPÆUS’ VICTUALS

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,13 whose delicate cocoon consists of only a single thickness.