87 



history of one species will furnish facts which may be applied in 

 all particulars to the other members of the family. A careful 

 study of each species is almost sure to bring out striking differ- 

 ences, and it is this fact that makes their study interesting and in- 

 structive. Eggs may be placed in difTerent situations, for example^ 

 over water or over mud, usually according to the species ; but at 

 other times it seems according to circumstances. Some species are 

 known to habitually attach their eggs to projecting stones in rip- 

 ples, others to foliage or any projecting object over stagnant water. 

 It appears that the commonest species and at the same time the 

 worst stock pests oviposit over stagnant water or over wet ground. 

 Larvae hatched from eggs placed over water must drop into the 

 water, and therefore a measure of success may be had by using 

 contact insecticides on its surface at hatching time. 



The method so long used of applying some oily or ill-smelling 

 substance to stock for the purpose of repelling the flies has certain 

 virtues that should not be lost sight of, but a single application is of 

 such short duration and the objection to making such applica- 

 tions to animals so common that if any other equally effective 

 measures could be brought out the former would become unpop- 

 ular. 



Since the injury caused by horseflies is produced only by the 

 adults, a remedy for this stage is most desirable, and it is to be 

 hoped that a careful study of the habits of this stage may reveal 

 points where successful attacks may be made. Porchinski, of 

 Russia, and Howard, of this country, have already made a notable 

 contribution along this line; and besides, the habit which the 

 adults of some species, at least, have of collecting in certain situa- 

 tions seems to offer promise of good results. In the few experi- 

 ments I have made in this connection it has been demonstrated to 

 my satisfaction that it is possible to get good results by systemat- 

 ically trapping the adults. 



