4l8 THE OX GAD-FLY. 



to the earth j and generally pass the chrysalid state 

 under cover of the first stone they meet with. 



From the posterior part of the body of the perfect 

 insect issues a wimble of wonderful structure. It 

 is a scaly cylinder, composed of four tubes, which 

 draw out like the pieces of a spying-glass : the last 

 of these is armed with three hooks, and is the gim- 

 let with which the insect bores through the tough 

 hide of horned cattle. When the egg is hatched, 

 the . grub feeds on the matter issuing from the 

 wound. The nidus forms upon the body of cattle 

 a lump, sometimes above an inch high. When the 

 larva is full grown, it breaks through the tumour, 

 and slides down to the ground in the cool of the 

 morning. It then digs itself a burrow, into which 

 it retires. Its skin hardens to a very solid shell, 

 where it is transformed to a chrysalis, and after- 

 ward to a winged insect. This shell has a small 

 valve at one end, fastened by a very slight liga- 

 ment ; without which, so careful is nature in the 

 preservation of her offspring, the insect would not 

 be able to escape from its confinement*. 



THE OX GAD-FLY f 



Has brown unspotted wings ; and the abdomen 

 is marked with a black band in the middle, and 

 has dusky yellow hairs at the tip. The front Is 



* Barbnt's Gen. Insect. 296. 

 + Synonyms. — Oestrus bovis. X.z»«.— JLarvas called Bott r Wor~ 

 muls, Wornuls, or Warblts. 



