Page:Popular Science Monthly Volume 58.djvu/261

Rh In all 23,087 flies were examined. They were caught in rooms in which food supplies are ordinarily exposed, and may safely he said to have been attracted by the presence of these food supplies. Of these 23,087 flies, 22,808 were Musca domestica; that is to say, 98.8 per cent, of the whole number captured belonged to the species known as the common house-fly. The remainder, consisting of 1.2 per cent, of the whole, comprised various species, the most significant ones being Homaloymia canicularis (the species ordinarily known as the 'little house-fly'), of which 81 specimens were captured; the stable-fly (Muscina stabulans), 37 specimens; Phora femorata, 33; Lucilia cæsar (screw-worm fly), 8; Drosophila amelophila, 15; Sarcophaga trivialis, 10; and Calliphora erythrocephala (the common blow-fly), 7.

Musca domestica is, therefore, the species of greatest importance from

the food-infesting standpoint; Homaloymia canicularis is important and Muscina stabulans is of somewhat lesser importance. Drosophila amelophila, although not occurring in the former list of abundant species, does rarely breed in excreta and is an important form; it would have been much more abundant in the records of house captures had more of these been made in the autumn, after fruit makes its appearance upon the dining tables and sideboards, since this species is the commonest of the little fruit-flies which are seen flying about ripe fruit in the fall of the year. The Calliphora and the Lucilia are of slight importance, not only on account of their rarity in houses, but because they are not, strictly speaking, true excrement insects. They