3024 



THE JOINTED ANIMALS 



Hover Flies 



CIRCULAR-SEAMED FLIES SUBORDER Cyciorrhapha 



This suborder, which is characterized by the circumstance that the pupa es- 

 capes from the larval skin through a circular aperture formed by the pushing off of 

 the head end, contains the majority of ordinary flies. It is divisible into two sec- 

 tions, the first of which includes those that present the normal method of develop- 

 ment, the young being hatched from eggs laid by the mother, although very rarely 

 the eggs hatch immediately before being laid. The second embraces those in which 

 the young are retained within the parent's body, and nourished at its expense until 

 the pupa stage is reached. The flies of the last category are for this reason gener- 

 ally called Pupipara. 



The family Syrphidce includes a number of species which, al- 

 though differing considerably in external form, may be distinguished 

 from other members of the suborder by the presence of the so-called spurious vein 

 in the wing a vein lying between the third and fourth longitudinal veins, and 



crossing the short transverse vein (marked in 

 the figure on p. 3011) which unites them. They 

 also bear considerable superficial resemblance, 

 both in color and shape, to various bees and 

 wasps. The best-known types are the hover 

 flies (Syrphus), drone flies (Eristalis), and 

 humblebee flies ( Volucella). The hover flies 

 of the genus Syrphus, which with their black 

 and yellow bands mimic wasps, are so named on 

 account of their habit of hovering in flower 

 gardens in summer, darting from blossom to 

 blossom, and often sustaining themselves poised 

 in mid-air, after the manner of a hawk. The fe- 

 males lay their eggs singly on leaves and stems 

 infested with plant lice; and the larvae devour 

 numbers of these pests, seizing them in a most 

 voracious manner, sucking them dry, and reject- 

 ing the empty skins. 



Like the hover flies, drone 



Drone Flies a . s *? * f \ * n 



flies {hnstahs) frequent flower 



gardens, where they may be seen in numbers on 

 various blossoms. As their name indicates, these 

 flies resemble honeybees, the likeness being so 

 close that it is difficult to persuade an uninitiated 

 person that they may be handled with impunity. 

 The resemblance, which is enhanced by the 

 ceaseless twitching of the abdomen, appears 

 indeed to be more deeply seated than might at 

 first be supposed, for spiders, which recognize 



HOVER FLY (Syrphus seleniticus). 



1. Fly; 2. Fly hovering; 3. I,arvse devouring 

 plant lice on leaf; 4. Larva; 5, 6, Differ- 

 ent views of pupa. (4, 5, 6, enlarged; 

 the rest natural size.) 



