430 ARTHROPODA 



like the orange scale, Aspidotus aurantii* and the worse San Jose scale, A. 

 pcniiciosus* recently spread through this country. The APHID.E, or plant lice, 

 are soft-skinned and with their honey-containing excrement form a substratum 

 fur the growth of injurious fungi. They reproduce largely by parthenogenesis, 

 but their spread is not rapid, since the usually viviparous females are wingless. 

 At times winged females appear and spread the pests. Winged males appear 

 in the autumn; the fertilized eggs endure the winter. Xone is more injurious 

 than Phylloxera vastatrix* of the grape, which with us does slight damage, but 

 in Europe has destroyed whole vineyards. Sub Order III. APTERA. Wing- 

 less bugs with direct development, commonly known as lice; three species attack 

 man, one living in the hair (Pediculus eaptlis*}, the others (P. vestimentorum* 

 and Phthinus inguinalis**) upon the body. Other species on other mammals. 



Order IX. Diptera. 



Like the Rhynchota, the Diptera, or flies, are sucking insects, but 

 the haustellum is different, consisting of a tube, formed of labium and 

 labrum, containing stylets which include, besides mandibles and maxillae 

 (often rudimentary), the hypopharynx (fig. 446). Only the anterior 

 win^s (hence Diptera) are developed, the hinder wings being replaced by 



the halteres or balancers, small drumstick-like struc- 

 tures richly supplied with nerves and functioning as 

 organs of equilibration (fig. 486). The thorax is, 

 as in the Hymenoptera, sharply marked off from head 

 a,nd abdomen, its somites frequently fused. The de- 

 velopment is holometabolous, two kinds of larvae and 

 pupae occurring. The larvae are always apodal, but 

 have either a distinct head with biting mouth parts 

 or ^y are headless and have a rudimentary sucking 

 apparatus (fig. 484). The pupae are correspond- 

 FIG. 484. Larva ingly either free with powers of motion, or are pupae 



of .4 nthom via canicn- - , , 



/ora(afterLeuckart). coarc tatae (p. 416). Development thus affords charac- 

 ters of systematic importance, and these are supple- 

 mented by differences in length of legs, antennae, haustellum, and in 

 body form. In number of species the Diptera stand next to the 

 Coleoptera; in number of individuals they far exceed them. 



Sub Order I. NEMOCERA. Elongate with long, many-jointed antennae, 

 long proboscis, long legs. The larvae live in damp places or in water, where, 

 lacking legs, they swim by movements of the body, capturing their prey with their 

 strong mouth parts. The pupae also can swim well. The aquatic larvae have 

 two respiratory tubes at the end of the abdomen; in the pupae they are on the 

 back. Best known are the innocuous crane flies (TiPULiD^;) and the mosquitos 

 (CuLiciD^:) with their numerous species affecting man, among them, Stegomyia* 

 which carry yellow fever, and Anopheles* which distribute malaria. The CECI- 

 DOMYID.-E include the injurious Hessian fly, Cecidomyia destructor* and the paedo- 

 genetic Miastor (fig. 456). Sub Order II. TANYSTOMA. Resemble the 

 Muscariae in the short stout bodies, short antennae and legs. Th^y resemble 



