ENTOMOLOGY 



positor and is frequently enclosed by one or two pairs of valves. In 

 Ephemerida the two inner valves are partly or entirely separate from each 

 other, forming two intromittent organs (Fig. 84). 



In male Odonata, the ejaculatory duct opens on the ninth abdominal 

 segment, but the copulatory organ is placed on the under side of the sec- 

 ond segment, to which the spermatozoa are transferred by the bending 

 of the abdomen. At copulation, the abdominal claspers of the male 

 grasp the neck of the female, and the latter bends her abdomen forward 

 until the tip reaches the peculiar copulatory apparatus of the male. 



The claspers of the male consist of a single pair, variously formed. 

 They are present in Ephemerida, Neuroptera, Trichoptera, Lepidoptera 

 (Fig. 85), Diptera and some Hymenop- 

 tera, though not in Coleoptera, and 

 often afford good specific characters, as 



FIG. 81. Sting of honey bee. A, i, 2, j, posi- 

 tions in three successive thrusts; s, sheath. B, 

 cross-section; c, channel; i, united inner valves, 

 forming the sheath; v, v, ventral valves, or darts. 

 A, after CHESHIRE; B, after FENCER. 



FIG. 82. Sting and poison appara- 

 tus of honey bee. ag, accessory gland; 

 p, palpus; pg, poison gland (formic 

 acid); r, reservoir; s, sting. After 

 KRAEPELIN. 



in Odonata. In butterflies of the genus Thanaos, the claspers are peculiar 

 in being strongly asymmetrical. In Odonata (Fig. 86, A) and Orthoptera 

 (Fig. 87, A) the superior appendages of the male often serve as claspers. 

 In many insects the tergum of the last abdominal segment forms a 

 small suranal plate (Fig. 87, B, sp) ; this sometimes supplements the clasp- 

 ers of the male in their function, as in Lepidoptera (Fig. 85, A, s). 



2. INTEGUMENT 



Insects excel all other animals in respect to adaptive modifications of 

 the integument. No longer a simple limiting membrane, the integument 



