THE WAX-GLANDS 



361 



substance, containing many crystals and a coagulable fluid, out of 

 which the egg-capsule (ootheca) is formed. (Miall and Denny.) 

 In the locusts the sebific or cement-gland (Fig. 298, s6) secretes a 

 copious supply of a sticky fluid, which is poured out as the eggs pass 

 out of the oviduct and agglutinates the eggs into a mass, forming 

 a thin coating around each egg, which from the mutual pressure 

 of the eggs causes the tough coating to be pitted hexagonally. In 

 other insects also (Triehoptera, Chrysopidse, Lepidoptera, etc.) there 

 are similar secretions for the protection or fastening of the eggs 

 when laid. 1 The Triehoptera lay their eggs either in or on the 

 surface of the water in bunches or in strings or in annular gelatinous 

 masses on stones or on plants. This jelly-like substance is secreted 

 by two highly developed paired anal glands. (Weltner, in Kolbe, 

 p. 621.) Also in certain dragon-flies (Libellula, Diplax, and Epi- 

 theca) the eggs are laid in jelly-like masses. 



With a similar secretion, spun from the end of the abdomen, the 

 Psocidte cover their little bunches of eggs laid on the under side of 

 leaves ; and the silk thread forming the egg-sac of the great water- 

 beetle (Hydrophilus) is secreted from such anal glands. 



g. The wax-glands 



Besides the honey-bee, which secretes wax in little scales on the 

 under side of the abdomen, the bodies of many other insects, such 

 as the plant and bark lice, as well as the Psyllidse, Cicadidae (espe- 

 cially Flata and Lystra), are covered with a waxy powder, or as in 

 Chermes, Schizoneura, Flata, etc., with 

 wool-like filaments of wax. 



FIG. 352. Under side of worker honey-bee, carrying wax 

 scales, x 3. After Cheshire. 



FIG. 353. Nymph of Lach- 

 nus, showing position of wax- 

 glands. Gissler del. 



1 For the mode of adhesion of Cynips eggs, see Adler in Deutsche Ent. Zeits. 1877, 

 p. 320. 



