The blue-bottle deposits her eggs, 500 or 600, preferably on dead fish, or flesh, and sometimes on the sores or the flesh of wounded animals, but both the house-flies preferably affect dung, carrion, garbage, and all kinds of fermenting vegetable matter. It has been commonly but not truly said that the principal breeding places of the house-fly are the mews and the farmyards where manure is allowed to accumulate; the house-fly has a preference for horse dung before cow dung, which is preferred by some other kinds of flies; however, near towns, the domestic dust-bins, heaps of market garbage, and deposits of town refuse give rise to a worse plague of house-flies than stables. All these flies deposit batches of white eggs, and are careful to place them as much as possible in crevices and shielded from exposure to strong light, or from draughts. The two house-flies and the blue-bottle have similar larval stages, but their larvæ, called maggots, differ. The larvæ avoid daylight and cannot withstand dryness. As the larvæ feed, they have the power of ejecting or excreting a juice, which dissolves the food before they imbibe the material; their mouths are suctorial and are destitute of teeth or biting jaws. The larva of the house-fly is an eyeless and legless maggot, one half inch long when full grown and extended; twelve cylindrical segments may be counted in its body, or even thirteen if we separately distinguish the small head segment, which may be withdrawn, and but little observable; five or six rear segments are of nearly equal stoutness when only half grown; afterwards counting from the three stoutish rear segments, the others taper towards the very small head. The middle and rear segments have pad-like bristly processes underneath, which aid the maggots in creeping, in which action they also make much use of the head segment's grappling hook. The maggots feed voraciously, but they seem, like the larvæ of the honey bee, to pass out very little anal excreta; some have thought that, like what is said of bee larvæ, no excrement is discharged until after the imago has emerged from the puparium; but such conduct seems altogether incredible. In the bee-hive doubtless the assiduous workers ever wash their babies clean and lick up all matter, just like domestic cats and dogs, when nursing their young. The larva of the blue-bottle, called a gentle, is proportionately larger but very similar, except that the rear segment possesses a ring of tubercles, which may have some useful function in connection with two breathing tracks, which have their orifices at that part of the body. The larva of the lesser house-fly is very peculiar; all its segments have projecting tubercles; its whole body is rather louse-shaped, having not cylindrical but somewhat flattened segments, of which the middle are the broader, and those near the head and tail the narrower.