332 



INTRODUCTION TO ZOOLOGY 



Family 2 : Syrphidae (the Hover-flies) 



Hover-flies are very plentiful in every garden, 



or Syrphus '^^^^'"^ ^^^ "^^7 ^^ s^^'i hovering over the flowers 



in the sunshine. With body motionless, and 



wings vibrating so 

 rapidly as to be al- 

 most indistinguish- 

 able, they feed on 

 the pollen of the 

 flowers, and then dart 

 rapidly away. 



They are rather 

 large flies, often hairy, 

 and of a brown 

 colour usually barred 

 with yellow, rather 



Fio. 251. — A Syrphid Fly, enlarged to show 

 Wing Veuatiou. (x3.) 



resembling bees or wasps at the first glance, though their 



thick bodies, with no sign of the remarkably slender " waist " 



of bees and wasps, very readily distinguish them when more 



carefully observed. Moreover, 



the veining of the wings is quite 



peculiar and characteristic, for at 



the free edge of the wing are two 



nervures which run parallel to 



the edge and are not crossed 



by any of the longitudinal 



nervures ; just behind these 



there is a deep bay (Fig. 251). 



Many of these Hover- flies 

 have larvae which live on plantsin 

 the garden, feeding on the green- 

 fly which they transfix on the 

 three sharp points of their mouth- 

 organs and hold aloft as they 

 feed. They are soft white legless 

 grubs tapering in front (Fig. 

 252). They constantly stretch 

 and contract their bodies as 

 they creep along after their prey. 

 They pupate on the plants, the larval body contracting and 



eg'^ ^nlAr5f«l. 



Fib. 2.52. — Syrphus 



(the Hover-fly), showing different 

 stages in its life-history. 



