34° 



COLLEGE ZOOLOGY 



Order 4. Plecoptera. — Stone-flies 

 (Fig. 263). — Insects with four membranous 

 wings; hind wings large and folded like a 

 fan; biting mouth-parts; metamorphosis 

 incomplete. 



The stone- fly nymphs live in brooks on 

 the underside of stones, and breathe by 

 means of filamentous tracheal gills which 

 extend out from just behind the legs. They 

 serve as food for fishes. 



Order 5. Isoptera. — Termites or White 

 Ants (Fig. 264). — Insects with four similar 

 wings, leathery in structure and lying flat 

 on the back, or wingless (workers); biting 

 mouth-parts; metamorphosis incomplete. 



The termites are social insects and live 

 in colonies. Each colony contains a queen 

 (Fig. 264, B) that lays all of the eggs, a 

 winged male (A) that fertilizes the queen, a 

 number of wingless workers (C) that build the nest, procure 



Fig. 263. — Order 

 Plecoptera. Stone- 

 fly, Perla maxima. 

 (From Sedgwick's 

 Zoology, after Pictet.) 



D 



Fig. 264. — Order Isoptera. Termites. 

 A, male or king of Termes. B, female or 

 queen of Termes. C, worker of Termes. 

 D, soldier of Termes. (From the Cambridge 

 Natural History; C and D, after Grassi.) 



