526 APHANIPTERA THYSANOPTERA CHAP. 



of the domestic fowl in Ceylon, and an allied form, Rhynchopsylla 

 pulex, fastens itself to the eyelids and other parts of the body of 

 birds and bats in South America. In Turkestan Vermipsylla' 

 alakurt attacks cattle ox, horse, camel, sheep fastening itself to 

 the body of the animal after the fashion of a tick. Eetaining 

 this position all through the winter, it becomes distended some- 

 what after the manner of the Sand-flea, though it never forms 

 a spherical body. The parts of the mouth in this Insect (Fig. 251) 

 are unusually long, correlative with the thickness of the skins of 

 the animals on which it lives. Grassi considers that the dog's 

 flea, Pulex serraticeps, acts as the intermediate host of Taenia. 



Great difference of opinion has for long prevailed as to 

 whether fleas should be treated as a Sub-Order of Diptera or as 

 a separate Order of Insects. Wagner and Kiinckel, who have 

 recently discussed the question, think they may pass as aberrant 

 Diptera, while Packard, 1 the last writer on the subject, prefers 

 to consider them a separate Order more closely allied to Diptera 

 than to any other Insects. Although widely known as Aphan- 

 iptera, several writers call them Siphonaptera, because Latreille 

 proposed that name for them some years before Kirby called 

 them Aphaniptera. Meinert considers them a separate Order 

 and calls it Suctoria, a most unfortunate name. 



Order VIII. Thysanoptera. 



Small Insects, with a palpigerous mouth placed on the under side of 

 the head and apposed to the sternum so as to be concealed. 

 With four slender wings, fringed with long hairs on one or 

 bojth margins, or with rudiments of wings, or entirely apterous. 

 Tarsi of one or two joints, terminated by a vesicular structure. 

 The young resemble the adult in general form, but there is a 

 pupal stadium in 'which the Insect is quiescent and takes no 

 food. 



The tiny Insects called Thrips are extremely abundant and 

 may often be found in profusion in flowers. Their size is only 

 from -Jjy to -3j- of an inch in length ; those of the latter magni- 

 tude are in fact giant species, and so far as we know at present 

 are found only in Australia (Fig. 253). As regards the extent 

 1 P. Boston Soc. xxvi. 1894, pp. 312-355. 



