FLY GRUBS. 37 



hurtful to many kinds of crops ; the Blowflies, which 

 cause great waste to meat in summer ; the Gadflies, 

 and a yevy large number of other kinds, which, by 

 means of their maggots, do boundless damage year by 

 year to the roots of Cabbage, Onions, and other 

 garden-crops, and likewise to the heart or stem of 

 the growing corn ; and many other kinds of various 

 habits. 



All flies of this order have only one pair of 

 wings ; occasionally they are wingless. The hinder 

 pair of wings is represented by a pair of appen- 

 dages, often like a slender pin with a small head ; 

 these are known as " poisers " (scientifically, Jialteres), 

 because they helj), or ajjpear to help, to poise or 

 balance the insect. Some of these insects feed by 

 suction, as in the case of the Gnats, to our great 

 •annoyance. 



The maggots, or larvae, are fleshy and (with few 

 exceptions) footless ; * sometimes, like the Daddy 

 Longlegs grub, they have a hard head, furnished with 

 nippers or jaws ; sometimes they have a soft mass 

 which answers for a head, commonly bearing a pair 

 of hooks instead of jaws, with which they clear out 

 the substance between the two sides of a Turnip-leaf, 

 or from the inside of an Onion-bulb, or other soft 

 material in which they may be feeding. 



The })upa-case, or chnjsaUs,yAv\e^ in shape; in some 

 kinds, as of the Gnats and Daddy Longlegs, for 

 instance, it is in shape much like the creature within, 

 with its limbs folded ; in many other kinds, as of the 

 Onion Fly, Carrot Fly and others, the pupa-case con- 

 sists of the hardened maggot- skin, which shelters the 

 forming fly within. 



* The maggots of two kinds of Flies (Kristalis and HclojiJiilus) are 

 peculiar for possessing seven pairs of what may be called a kind pf 

 claw-like feet. These maggots are known as " rat-tailed larvte," 

 from the hinder part of the body being lenj.'thened into a long slender 

 tail-like tube, whereby they can draw in air from above the damj) or 

 muddy places in which the maggots lie. 



