104 BRITISH INSECTS 



germs of diseases, and every possible means for its 

 suppression should be adopted. Both Stomoxys and 

 the true house-fly breed chiefly in stable refuse. The 

 bristly grey flesh-flies and their allies make up a dis- 

 tinct sub-family viz., Savcophagince. Most of the 

 species are viviparous i.e., the eggs are hatched in 

 the parent's body, and the young maggots are sub- 

 sequently dropped upon suitable food. Another 

 sub-family l comprises numerous flies with very bristly 

 bodies. They lay their eggs on caterpillars, into 

 whose tissues the maggots burrow. These parasites 

 often cause disappointment to the collector. The 

 afflicted caterpillars usually preserve sufficient vitality 

 to pupate ; but the pupae eventually disclose Tachinid 

 flies instead of the looked-for moths. 



The family Anthomyiidcz comprises numerous small 

 species, many of which look like tiny house-flies. In 

 some instances the maggots feed on decaying matter 

 of various kinds ; in others they burrow into living 

 plants, and work considerable havoc. One species 

 called Hylemia antiqua is the " onion-fly," whose 

 maggots sometimes do so much damage to onion 

 crops. 



A few highly specialized flies of strange habits 

 make up the family Hippoboscida. They are all blood- 

 sucking parasites, and live upon the bodies of mam- 

 mals, or, more rarely, birds. The maggots are 

 produced viviparously, and fully developed, so that 

 they pupate shortly after leaving the parent's body. 

 The best known example of this family is the wingless 

 " ked," 2 often erroneously called the "sheep-tick." 

 Other species are winged, and one of these, the New 

 Forest-fly, 3 has on more than one occasion attracted 



1 TachinincB. 2 Melophagus ovinus. 3 Hippobosca equina. 



