416 



DIPTERA. 



barley, from six to ten larvae being found in each, and by de- 

 stroying the flowers render the ear sterile. Oscinis frit Linn, 

 in Europe inhabits the husks of the barley, and destroys one- 

 tenth of the grain. Linnteus calculated the annual loss from 

 the attacks of this single species at half a million dollars. 

 Ploughing and harroAving are of no use in guarding against 

 these insects, as they do not transform in the earth ; the best 

 remedy lies in the rotation of crops. Many of these small 

 flies, like the micro-lepidoptera, are leaf-miners, and are not 



readily distinguished from 

 them when in the larva state. 

 Of the genus Phora^ a 

 European species (P. incras- 

 sata Fig. 339 ; a, larva ; 6, 

 puparium) frequents bee 

 hives, and is thought by some 

 Fig- 339. iq produce the disease 



which is known among apiarians as "foulbrood." 



In the pupiparous Diptera, namely, those flies which are born 

 as pupae from the body of the parent, the lar^a state having 

 been passed within the oviduct, the thorax is more closely 

 agglutinated than before ; the head is small and sunken in 

 the thorax, and in the wingless species this consolidation of 

 the head and thorax is so marked as to cause them to bear a 

 remarkable resemblance to the spiders. Spider-like in their 

 looks, they are spider-like in their habits, as the names Spider- 

 flies, Bat-ticks and Bird-ticks, imply a likeness to the lower 

 spiders or ticks. The antenuiB are very deeply inserted and 

 partially obsolete ; the labrum is ensheathed by the maxillae, 

 and the thoracic nervous ganglia are, as in the Arachnida, 

 concentrated into a siuQ-le mass. 



HippOBOSCiD^ Westwood. The Forest-flies and Sheep 

 Ticks are characterized by the horny and flattened bod}^, the 

 horizontal flattened head received into the front edge of the 

 thorax, the large eyes, the rudimentary papilla-like antennae 

 placed very near together, and the proboscis is formed by the 

 labrum and maxillae, whose palpi are wanting ; the labium is 

 very short ; wangs with the veins present only on the costal 



