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HOUSE-FLIES. 

 W. Hague Harrington, Ottawa. 



It will be necessary to define what a fly is, for the name is very commonly applied 

 to many insects which belong to very different orders. We have, for instance, saw-flies, 

 butter-flies, fire-flies, dragon-flies, and shad-flies, belonging respectively to the Hymen- 

 optera, Lejndoptera, Coleoptera, Neuroptera. Ail of these have four wings, in common 

 with the majority of insects ; whereas the true flies have only two and constitute the 

 order of Diptera, which name is formed from the Greek words dis, twice, and pteron, a 

 wing. Although the order is not generally a favourite one with Entomologists, its study 

 will reveal a great many curious and important facts in connection with insect life. Its 

 members are not so handsome nor as large as those of the Lepidoptera and Coleoptera, 

 nor do they construct complex dwellings like the Hymenoptera, yet their larvae are found 

 living under the most varied and wonderful conditions, and not unfrequently greatly 

 affecting man's welfare, as do often also the perfect insects. 



All insects (by the classification used in this country) are divided into seven orders 

 according to the character of the wings, and these orders are again arranged in two 

 series — one having mouth-parts adapted for biting and masticating their food, the second 

 having the analogous parts modified to form a sucking apparatus. The Diptera belong to 

 the latter. 



It has been estimated that there are about 10,000 species of flies indigenous to 

 North America, of which not more than one-fourth have been described, so that plenty 

 of material yet remains for investigation, and doubtless many new species would reward 

 an industrious collector in any section of Canada. 



No other insects, perhaps, occur in such profusion as do flies. As soon as the first 

 mild days arrive, clouds of small gnat-like forms appear, and as the season progresses 

 new species are continually emerging. At times the air seems literally full of these 

 minute beings, which swarm alike in woods or over fields and waters, very frequently 

 making their presence felt as well as seen. 



In the larval state they occupy a very important place in the economy of nature, 

 and while some species — such as the hessian-fly and wheat-midge — are most inimical to 

 man's interests, the majority subsist by destroying substances which otherwise might 

 remain to infect and contaminate the air. The aquatic species — such as the black-flies 

 — live principally on decaying vegetable or animal matter in the water, while the 

 greater number of terrestial forms subsist upon similar substances, which they rapidly 

 consume. 



So rapidly does this consumption proceed that Linnaeus, referring to the flesh-flies, 

 stated that three of them with their progeny could eat up a dead horse as quickly as a 

 lion could. 



Notwithstanding that house-flies abound everywhere, or at least where man has his 

 habitation, comparatively few persons know the most simple facts concerning their life- 

 histor} 7 and transformations. Even among Entomologists there is much of vagueness 

 in regard to these matters, owing partly to few having fully investigated the habits of 

 the house-fly, and partly to its being often confounded with allied species. There ap- 

 peared last year, in a popular magazine, an article taken from "Science Gossip," and 

 professing to treat of the development of Musca domestica — as the house-fly is named by 

 Entomologists — in which it. was stated that the larvae were reared in meat upon which 

 the fly had deposited its eggs. This shows at once that the description was really that 

 of the development of one of the meat-flies; for, so far as I am aware, the house-fly his 

 never been known to deposit its eggs upon meat. 



The house-fly of this country is now known to be identical with that of Europe, 

 although the late Dr. Harris described it under the name of Musca harpyia. Even 

 in Europe but little attention has been given to its habits since its name was be-" 

 stowed upon it by Linnaeus. 



