50 AN INTRODUCTION TO ENTOMOLOGY. 



GG. Base of abdomen strongly constricted. {Ants et a/.') 



X. HVMENOPTERA. 

 BBB. Mouth-parts formed for sucking. 



C. Small abnormal insects in which the body is either scale-like or gall- 

 like in form, or grub-like, and clothed with wax. The waxy covering 

 may be in the form of powder, of large tufts or plates, of a continuous 

 layer, or of a thin scale, beneath which the insect lives. {Coccidce.) 



VI. Hemiptera. 



CC. Body more or less covered with minute scales, or with thick long 



hairs. Prothorax not free {i.e., closely united with the mesothorax). 



Mouth-parts usually consisting of a long " tongue" rolled beneath the 



head. VII. Lepidoptera. 



CCC. Body naked, or with isolated or bristle-like hairs. 



D. Prothorax not well developed, inconspicuous or invisible from above. 

 Tarsi five-jointed. Mouth-parts developed into an unjointed trunk ; 

 palpi present. VIII. Diptera. 



DD. Prothorax well developed. 



E. Body strongly compressed ; tarsi five-jointed. {Fleas.) 



VIII. Diptera. 

 EE. Body not compressed ; tarsi one-, two-, or three-jointed. 



F. Last joint of tarsi bladder-like or hoof-like in form and without 

 claws; mouth-pans forming a triangular, unjointed beak; palpi 

 present. IV. Physopoda. 



FF. Last joint of tarsi not bladder-like, and furnished with one or 

 two claws ; mouth-parts forming a slender, usually jointed beak ; 

 palpi wanting. V. Hemiptera. 



AA. Winged. 



B. With two wings. 

 C. First pair of wings transformed into club-shaped appendages. {Stylo- 



Pidcs.) IX. COLEOPTERA. 



CC Second pair of wings rudimentary or wanting. 

 D. Wings horny, leathery, or parchment-like. 



E. Mouth-parts formed for sucking. Wings leathery, shortened, or 

 membranous at the tip. V. Hemiptera. 



EE. Mouth-parts formed for biting. Jaws distinct. 



F. Wings horny, without veins. Hind legs not fitted for jumping. 



IX. COLEOPTERA. 



FF. Wings parchment-like, with a network of veins. Hind legs 

 fitted for jumping. III. Orthoptera. 



DD. Wings membranous. 



E. Abdomen with caudal filaments. Mouth-parts rudimentary. 

 F. Halteres wanting. {Cloeon and Cams, in Ephemerida^) 



IV. PSEUDONEUROPTERA. 



FF. Halteres present (males of Coccidse). V. Hemiptera. 



EE. Abdomen without caudal filaments. Halteres in place of second 



wings. Mouth-parts formed for sucking. VIII. Diptera. 



BB. With four wings. 



C. The two pairs of wings unlike in structure. Prothorax freely movable. 



