332 



INTRODUCTION TO ZOOLOGY 



CHA!'. 



or 



Family 2 : SYRPHIDAE (THE HOVER-FLIES) 



Hover-flies are very plentiful in every garden, 

 where they may be seen 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, 



FIG. 251. -A Syrphid Fly, enlarged to show an , d f * * TOW * 

 Wing Venation. ( x 3.) colour usually barred 



with yellow, rather 



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 plants in 

 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 FIG. 

 and contract their bodies as 

 they creep along after their prey. 

 They pupate on the plants, the larval body contracting and 



ski 



252. Syrphus seleniticus 

 (the Hover-fly), showing different 

 stages in its life -history. 



