1G4 STATE BOAED OF AGKICULTUEE. 



hy hooks, but iu other cases only by fleshy tubercles. The stigmata or breath- 

 ing pores are placed iu one or two scale-like plates near the usually enlarged 

 posterior extremity of the maggots. The maggots moult twice. Their food is 

 usually, if not always, the puss or matter which arises from the irritation which 

 they cause. 



They go into the earth to pupate. The pupa is what is termed coarctate ; 

 that is, it is in form of a seed, the insect being surrounded by its last larval skin, 

 ■which forms a smooth covering and entirely hides the wings, legs, etc., of the 

 prospective fly. 



There are uumerous species of these bot-flies, each of which deposits on some 

 particular mammal, and usually in some definite place. In tropical America 

 there are species that infest man, Avorking in tumors under the skin, very much 

 after the style of our cattle bot-fly, soon to be described. 



There are really two well marked divisions of these flies, founded on the posi- 

 tion of the larvre in the animal infested. Some work just under the skin as in 

 the cattle and squirrel bot-flies, while others work in the natural cavities of the 

 -l)ody, and unlike most of the others, may inflict serious harm to their hosts. 



A matter of interest, and one really worthy to excite our wonder, may well be 

 mentioned right here. It is the extreme nervous action, often indicating dire 

 alarm, with which animals receive the flies as they come to deposit their eggs. 

 You have all of you observed this in the horse and sheep. The veriest hack of 

 a horse, one that has seen hard service for a score of years, will jerk its head as 

 if pierced by a needle. This show of dread is no less marked with cattle and 

 other quadrupeds, on which these flics practice nidification. The reason for 

 this alarm is fpiite obscure. It would be supposed, and is probably very geuer- 

 4illy thought, that the flies, like bees, have the power to make their presence 

 felt. But this is not true, as anatomy well proves, for the mouth and oviposi- 

 tor are so weak and yielding that neither could possibly injure, even the most 

 sensitive membrane ; then certainly the tough skin of the ox and the horse 

 could feel no hurt. It has also been supposed that a wise instinct, prompted by 

 j^rospective danger, makes the sharp clear tone of the bot-fly's hum a note of 

 alarm, and hence the uncontrollable fear of those mammals which are liable to 

 .attack. The objection to this reasoning is, that with the deer and our cattle, 

 the evil is not one of danger or even of great inconvenience, as will appear, and 

 in such cases the wise instinct greatly blunders. A third explanation, and as I 

 think, the most tenable one, is that this unreasoning dread is of nervous origin. 

 These animals learn to associate the hum of insects with pain. They are ever 

 and anon feeling the stab of the keen, stinging lancets of the various deer and 

 horse flies, and as the bot-flies dart toward them, their presence made all the 

 more obvious by their loud note, the poor jiersecuted animals, impelled by iier- 

 Tous impulse, become frantic ere there is chance to learn that mere noise is not 

 to be dreaded. Yet even here impulse may be of great service, for in fleeing 

 from apparent evil, a real danger may be held at bay. 



Horse Bot-FJij, — Gastrophilus equi, Fair. 



The horse bot-fly is certainly the most commonly observed, if not the most to 

 be dreaded, of all our species. Tliere are, too, more than one species attacking 

 the horse, but as the one named above is by far the most common, and as the 

 habits of all are much the same, I shall rest content witli detailing the life, his- 

 tory, etc., of this one. 



