ANIMAL-GALLS. 355 



horses, is ascertained beyond a doubt to deposit her eggs 

 upon the hair, and as insects of the same genus almost 

 invariably proceed upon similar principles, however much 

 they may vary in minute particulars, it may be inferred 

 with justice, that the breeze-flies which produce galls do 

 the same. The description given by Mr. Bracey Clark, of 

 the proceedings of the horse breeze-fly, is exceedingly 

 interesting. 



" When the female has been impregnated, and her eggs 

 sufficiently matured, she seeks among the horses a subject 

 for her purpose, and approaching him on the wing, she 

 carries her body nearly upright in the air, and her tail, 

 which is lengthened fo)^ the purpose* curved inwards and up- 

 wards ; in this way she approaches the part where she 

 designs to deposit the egg ; and suspending herself for a 

 few seconds before it, suddenly darts upon it and leaves 

 the egg adhering to the hair ; she hardly appears to settle, 

 but merely touches the hair with the egg held out on the pro- 

 jected point of the abdomen.^ The egg is made to adhere by 

 means of a glutinous liquor secreted with it. She. then 

 leaves the horse at a small distance, and prepares a second 

 egg, and poising herself before the part, deposits it in the 

 same way. The liquor dries, and the egg becomes firmly 

 glued to the hair : this is repeated by these flies till four or 

 five hundred eggs are sometimes placed on one horse." 



Mr. Clark farther tells us, that the fly is careful to select 

 a part of the skin which the horse can easily reach with his 

 tongue, such as the inside of the knee, or the side and back 

 part of the shoulder. It was at first conjectured, that the 

 horse licks off the eggs thus deposited, and that they are by 

 this means conveyed into its stomach ; but Mr. Clark says, 

 " I do not find this to be the case, or at least only by accident ; 

 for when they have remained on the hair four or five days, 

 they become ripe, after which time the slightest application 

 of warmth and moisture is sufficient to bring forth, in an 



* These circumstances afford, we think, a complete answer to the 

 query of Kirby and Spence— "There can be little doubt (or else what 

 is the use of such an apparatus ?) that it bores a hole in the skin." — 

 Introd. i. 162, 2nd edit. 



