34 



ON SOME COMMON INSECTS 



WHICH AFFECT 



THE HOESE, THE OX AND THE SHEEP. 



Compiled by Edmund Baynes Eeed, London, Ontario. 



1. The Horse Breeze-Fly {(Estrus[gasterophilus] equi, Fjlb). 



2. The Ox Bot-Fly {(Estrus bovis, Clark). 



3. The Sheep Breeze-Fly (Cephalcemia [CEstrus] ovis, Linn). 



The insects above named, whose history and habits we propose to lay before our 

 readers, belong to that division of the insect world commonly included under the name of 

 Flies. 



They are known however to science as Diptera, from two Greek words dis, two, and 

 2)teron, wing, and may be shortly described as suctorial insects, possessing in the perfect 

 state only two membranous wings. 



Several of the most eminent Entomologists, such as Reaumur, De Geer, Fischer, 

 have devoted considerable attention to the natural history of these flies, but it is to the 

 laborious and thorough investigation of the celebrated English Veterinary Surgeon, Bracy 

 Clark, that we are indebted for a very complete history of many of the members of the 

 particular genus now before us, the (Estri, whose popular names of Breeze, Gad and Bot- 

 flies, are so well known to every stockbreeder. 



Each species of (Estrus is parasitic upon a peculiar species of mammiferous herbivor- 

 ous animals, and selects with wonderful instinct as the spot in which to deposit its eggs, 

 that portion of the body of the animal which is best adapted for the welfare of its pro- 

 geny, that is in places either where the larvae when hatched may burrow into the back or 

 other part of the body, or where the larvae may be removed by the tongue of the animal 

 itself into its mouth, and thence to the stomach, in which, exposed to a temperature of 

 more than one hundred degrees Fahrenheit, they remain until full grown, when in either 

 case they quit the body, and making their way to the earth undergo their transformations 

 in the ground. 



Providence has doubtless created these animals to answer some beneficent purpose. 

 Mr. Clark conjectures that they act as counter irritants upon the system of those large 

 animals they attack, such as the horse, ox and sheep ; and by acting the part of perpetual 

 stimuli or blisters, do modify the eff'ects of grass feeding and repletion. Of course when 

 certain limits are exceeded these insects become the causes of diseases, and sometimes 

 even of death. 



According to Mr. Westwood, the larvae or grubs of (Estri exhibit three principal va- 

 riations in their habits, being either cutaneous^ when the grubs (commonly called Worrils, 



