430 Insect Architecture. 



produces the maggots well known by the name of bolts in 

 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 in- 

 teresting. 



"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 for 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 projected 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 



* 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." lutrod. i. 162, 2nd edit. 



