512 THE INVERTEBRATA 



families are included here, to some of which belong such serious 

 agricultural pests as the frit-fly of oats^ Oscinus frit^ and Chlorops 

 taeniopus the gout-fly of barley. In such cases, the larvae bore into 

 the growing shoot, or into the stem. Larger and better known are 

 the saprophagous house-fly Musca and the blow-fly Calliphora. The 

 larva of Hypoderma lineatum is parasitic in the bodies of cattle 

 causing "warbles" on the backs of affected animals, while Gastro- 

 philus equi, the bot-fly, is parasitic as a larva in the alimentary tract of 

 horses. 



The Tachinidae are important as parasites, chiefly of larval 

 Lepidoptera. Thus Ptychomyia remota is responsible for the very 

 effective control of the Levuana moth, Levuana iridescens, of Fiji. 



Blood-sucking muscids are important, e.g. Glossma, as the vector 

 of trypanosomiasis causing sleeping sickness of man and cattle disease 

 in Africa. The tsetse flies are pupiparous, larvae being nourished by 

 special glands opening into the genital tract. The larvae are deposited 

 as soon as fully grown and pupate immediately. 



A number of members of this order present a greatly modified 

 structure resulting from an ectoparasitic habit. They are known as 

 the Pupipara, being similar in their viviparity to Glossina. The follow- 

 ing examples may be quoted. Hypobosca is a winged leathery fly with 

 body dorso-ventrally compressed, and is an ectoparasite of cattle. 

 Melophagus is a wingless species, similarly associated with sheep, 

 familiarly known as the sheep tick. Nycteribia is a wingless form 

 parasitic on bats. 



Order APHANIPTERA (Fleas) 



Wingless insects, ectoparasitic on warm-blooded animals; laterally 

 compressed with short antennae reposing in grooves; piercing and 

 sucking mouth parts, maxillary and labial palps present; coxae large; 

 tarsus five-jointed; larva legless; pupa exarate, enclosed in a cocoon. 



These insects are perfectly adapted to an ectoparasitic existence 

 by their laterally compressed bodies, prominent tarsal claws, well- 

 developed legs suitable for running between the hairs of their host 

 and for jumping, and by their mouth parts (Fig. 351). They only 

 exhibit slight relationship to one other order, viz. Diptera, by their 

 metamorphic features and to a less degree by their mouth parts. 



The mouth parts consist of a pair of long serrated mandibles, a 

 pair of short triangular maxillae with palps, and a reduced labium 

 carrying palps. There is a short hypopharynx and a larger labrum- 

 epipharynx reminiscent of the Diptera. The labial palps, held together, 

 serve to support the other parts, a function which is performed by the 

 labium in the Diptera. In piercing, the mandibles are most important 

 and the blood is drawn up a channel formed by the two mandibles 



