4 ENTOMOLOGY. 



forms the ventral side of the abdomen, and meets the pleu- 

 rum on the side of the body. 



In the female (Fig. 1, B) the abdomen tapers some- 

 what toward the end of the body, to which are appended 

 the two pairs of stout, hooked spines, forming the oviposi- 

 tor (Fig. 1, B, r, r'). The anus is situated above the upper 

 and larger pair, and the external opening of the oviduct 

 is situated between the smaller and lower pair of spines; 

 it is bounded on the ventral side by a movable, triangular 

 acute flap, the egg-guide (Fig. 1, B, e g, and Fig. 4). 



The thorax, as seen in Fig. 1, consists of three seg- 

 ments, called the prothorax, mesothorax, and metathorax, or 

 fore, middle, and hind thoracic rings. They each bear a 

 pair of legs, and the two hinder each a pair of wings. The 

 upper portion (tergum) of the middle and hind segments, 

 owing to the presence of wings and the necessity of freedom 

 of movement to the muscles of flight, is divided or differ- 

 entiated into two pieces, the scutum and scutellum* 

 (Fig. 1), the former the larger, extending across the back; 

 the scutellum being a smaller, central, shield-like piece. 

 The protergum, or what is usually in the books called the 

 prothorax, represents either the scutum or both scutum 

 and scutellum, the two not being differentiated. 



The fore wings are long and narrow, and thicker than 

 the hinder, which are broad, thin, and membranous, and 

 most active in flight, being folded up like a fan when at 

 rest and tucked away out of sight under the fore wings, 

 ■which act as wing-covers. 



Turning now to the side of the body under the insertion 

 of the wings (Fig. 2), we see that the side of each of the 

 middle and hind thoracic rings is composed of two pieces, 

 the anterior, epistemum, resting on the sternum, with the 

 epimerum behind it; these pieces are vertically high and 



* There are in many insects, as in many Lepidoptera, Hymenoptera, 

 and Neuroptera, four tergal pieces — i.e., proescutum, scutum, scutel- 

 lum, and postscutellum, the first and fourth pieces being usually 

 very small and often obsolete. 



