160 INVERTEBRATE ANIMALS. 



ly erect when at rest (Fig. 71, c), by having club-shaped an- 

 tennae, and by having a chrysalis (#), which is almost always 

 naked and angular, and is generally attached to some solid 

 object by silken threads variously disposed. 



The Moths are mostly active during the night-time, when 

 they are said to be nocturnal. Many of them, however, are 

 " crepuscular " that is to say, they are active during the hours 

 of twilight ; and a few come out in broad daylight and in the 

 brightest sunshine. The pupaa, or chrysalides, are never an- 

 gular, as in the case of the butterflies. 



Apart from the destruction committed by the Caterpillars 

 of some of the Lepidoptera, the only members of the order 

 which are of importance to man are the various species of 

 Bombyx, from which silk is derived. Several species are cul- 

 tivated for this purpose, but by far the most valuable is the 

 common Silk-moth (Bombyx Mori\ which owes its name to 

 the fact that the larva feeds upon the leaves of the common 

 Mulberry (Morus nigra). It is hardly necessary to say that 

 raw silk is derived from the " cocoon," or silken case in which 

 the caterpillar enwraps itself before becoming a chrysalis. 

 Most of the raw silk is derived from France, Italy, China, and 

 the East Indies. 



ORDER X. HYMENOPTERA (Gr. humen, membrane ; pteron, 

 wing). In this order all the four wings are present, as a rule, 

 and they are all membranous in texture, with few nervures 

 (Fig. 72). The mouth is always furnished with biting-jaws or 

 mandibles, but often is adapted for suction as well. The fe- 

 males have the extremity of the abdomen furnished with an 

 instrument connected with the process of laying eggs (ovi- 

 positor) ; and in very many cases this becomes the powerful 

 defensive weapon known as the sting. The metamorphosis is 

 complete. 



The Hymenoptera form a very extensive order, comprising 

 the Bees (ApidcB), the Wasps ( Vespidce), the Ants (Formi- 

 cidce), the Saw-flies (Tenthredimdce, Fig. 72), and the Ich- 

 neumons. The Bees and Wasps are well known as forming 

 social communities, though solitary members of both are not 

 uncommon. In both groups these organized communities con- 

 sist of a vast number of undeveloped females, or " neuters " 

 the so-called " workers " presided over by a single fertile fe- 

 male, or " queen," or containing several such. The males are 

 only produced at certain seasons, and they constitute the so- 

 called " drones " of a hive of bees. The workers discharge all 



