AXIMAL-GALLS. 



357 



like a horse or an ox, take refuge in the water, it lias 

 recourse to a rut or dry dusty road, holding its nose close 

 to the ground, thus rendering it difficult for the fly to get 

 at the nostril. 



a, The belly of the grub, b. Its back, c, The tail of the grub, greatly niasnifled. d, The 

 buujp, or gall, having its external aperture filled with ihe tail of the grub. 



When the egg of the ox-breeze fly (^Hypoderma bovis, Latr.) 

 is hatched, it immediately (if Mr. Bracey Clark be correct) 

 burrows into the skin ; while, according to Eeaumur, it is 

 hatched there. At all events, the grub is found in a bump 

 on the animal's back, resembling a gall on a tree, — " a 

 place," sa3^s Eeaumur, " where food is found in abundance, 

 where it is protected from the weather, where it enjoys at 

 all times an equal degree of warmth, and where it finally 

 attains maturity."* When in an advanced stage, the 

 bumps appear much like the swellings produced upon the 

 forehead by a smart blow. These, with the grubs, are 

 represented in the foregoing figure, and also at page 359. 



Every bump, according to Reaumur, has in its inside a 

 cavity, which is a lodging proportionate to the size of the 

 insect. The bump and cavity also increase in proportion 

 to the growth of the grub. It is not until about the middle 

 of May that these bumps can be seen full grown. Owing 

 to particular circumstances, they do not all attain an equal 



* Mem. iv. 540. 



