42 THE STUDY OF INSECTS 



I. Tarsi two- or three-jointed. 



J. Hind wings smaller than the fore wings. 



K. Cerci present; body less than three millimeters in length. 



p. 62 ZORAPTERA 



KK. Cerci absent; larger insects, p. 83 Corrodentia 



JJ. Posterior wings as large as or larger than the anterior ones. 

 (Certain stoneflies). p. 81 Plecoptera 



II. Tarsi four- or five-jointed. 



J. Abdomen with setiform, many-jointed anal filaments (Certain 



mayflies), p. 74 Ephemerida 



JJ. Abdomen without many-jointed anal filaments. 



K. Prothorax horny. First wings larger than the second, naked 

 or imperceptibly hairy. Second wings without or with 

 few, unusually simple, veins. Jaws (mandibles) well de- 

 veloped. Palpi small, p. 329 Hymenoptera 



KK. Prothorax membranous or, at the most, parchment-like. 

 Second wings as large as or larger than the first, folded 

 lengthwise, with many branching veins. First wings 

 naked or thinly clothed with hair. Jaws (mandibles) in- 

 conspicuous. Palpi long. Moth-like insects, p. 180 



Trichoptera 



AA. Wingless or with vestigial or rudimentary wings. 



B. Insects with a distinct head and jointed legs, and capable of locomotion. 

 C. Aquatic insects. 



D. Mouth-parts fitted for piercing and sucking. 



E. Free-swimming nymphs, p. 94 Hemiptera 



EE. Larvae parasitic in sponges (Sisyridas). p. 66 Neuroptera 



DD. Mouth-parts fitted for chewing. 



E. Either somewhat caterpillar-like larvae that live in portable cases or 

 campodeiform larvae that spin nets for catching their food. (Caddice- 



worms). p. 180 Trichoptera 



EE. Neither case-bearing nor net-spinning larvae. 



F. Naiads, that is, immature insects that resemble adults in having the 

 thorax sharply differentiated from the abdomen, and, except in very 

 young individuals, with rudimentary wings. 

 G. Lower lip greatly elongated, jointed, capable of being thrust forward, 



and armed at its extremity with sharp hooks, p. 77 Odonata 



GG. Lower lip not capable of being thrust forward. 



H. Usually with filamentous tracheal gills on the ventral side of the 



thorax, p. 81 Plecoptera 



HH. Tracheal gills borne by the first seven abdominal segments. 



p. 74 Ephemerida 



FF. Larvae, that is, immature forms that do not resemble adults in the 

 form of the body, and in which the developing wings are not visible 

 externally. 

 G. Several segments of the abdomen "furnished with prolegs. p. 183 



Lepidoptera 



GG. With only anal prolegs or with none. 



H. With paired lateral filaments on most or on all of the abdominal 



segments. (Sialidae). p. 66 Neuroptera 



See also Haliplidae and Gyrinidae. p. 127 Coleoptera 



HH. Without paired lateral filaments on the abdomen, p. 127 



Coleoptera 



CC Terrestrial insects. 

 D. External parasites. 



E. Infesting the honey-bee. (Braula). p. 286 Diptera 



EE. Infesting birds or mammals. 



F. Body strongly compressed. (Fleas), p. 326 Siphonaptera 



FF. Body not strongly compressed. 



G. Mouth-parts formed for chewing. (Bird-lice), p. 85 . . . Mallophaga 

 GG. Mouth-parts formed for piercing and sucking. 



H. Antennae inserted in pits, not visible from above. (Pupipara). 



p. 286 Diptera 



HH. Antennas exserted, visible from above. 



