394 THE ANIMAL PARASITES OF MAN 



(3) Orthoptera. Four wings ; front pair coriaceous or leather-like, usually 



smaller than the other pair, which are of more delicate texture 

 and contract in repose like a fan ; mandibulate ; metamorphosis 

 complete. 



(4) Thysanoptera. Four very narrow fringed wings ; mouth imperfectly 



suctorial ; metamorphosis slight. 



(5) Hemiptera. Four wings ; the front pair either all transparent or 



with the basal half leathery ; mouth suctorial ; metamorphosis 

 slight. 



(6) Diptera. Two membranous wings only ; mouth suctorial, very 



varied ; metamorphosis complete. 



(7) Lepidoptera. Four large wings covered with scales ; mouth suc- 



torial ; metamorphosis great. 



(8) Hymenoptera. Four membranous wings ; front pair larger than hind, 



which do not fold up in repose ; mandibulate mouth, sometimes 

 with a tubular proboscis ; metamorphosis complete. 



(9) Coleoptera. Four wings, the front pair hard and horny (elytra), 



meeting in a line over the back and covering the delicate hind 

 pair ; mouth mandibulate ; metamorphosis complete. 



There are two other well known arrangements, namely, Packards 1 and 

 Brauers, 3 of recent date, but the one given here, which is based on Lin- 

 naeus' grouping by Dr. Sharp, is by far the simplest. F. V. T.] 



I. Rkyncota? 



The lower lip forms a long thin tube that can be turned back (rostrum), 

 and within which the setaceous mandibles and maxillae are situated ; the 

 first thoracic segment is not united with the two posterior ones ; the 

 anterior wings are usually leathery as far as the centre. 



(a) Rhynchota aptera s. parasitica. 

 Fam. Pediculidce (Lice). 



The lower lip is transformed into a projecting rostrum provided with 

 barbed hooklets in which the hollow extensile sucker (maxillae and man- 

 dibles) is situated ; no wings ; no metamorphosis ; only simple eyes ; the 

 antennae are five-jointed, the feet possess hook-like terminal joints ; the 

 barrel shaped eggs (nits) are deposited on the hair of the host. 



1 American Naturalist, xx., p. 808, 1886. 



2 " Syst. Zool. Studien," 5. B. Ak. Wien., xci., 1885, Abth. i., p. 374. 



3 [Usually known as Hemiptera. There are two sub-orders, Heteroptera and 

 Homoptera. The former have the base of the front wings coriaceous ; the latter have 

 all four wings membranous. The Homoptera are Aphides or Plant Lice and Scale 

 Insects (Coccidte), none of which attack man. F. V. T.] 



