It is another great mistake to suppose that an extra tasty food material is desirable as a bait. The same kind of mistake is made by people baiting a mouse trap with toasted cheese, whilst a bit of dry bread, or better still, a green pea, would much better entice a common mouse. Strong smelling and saccharine foods immensely attract the blue-bottle and the wasp, which are thus enticed indoors and induced to become occasional visitors to our tables; but the house-fly requires little of such lures; indoors she is an inquisitive prospector, who will never pass by any moist material without testing its quality. Moreover, the use of poisoned milk, or even jam, should be rather avoided for fear of injury to dog or cat; furthermore, it is dangerous to place a piece of bread in a saucer of liquid fly-poison, as is sometimes done, to serve as a sop and as a standing stage. However, there is one good lure well worth mentioning; it is beer-dregs with or without a little sugar; moistened yeast is good, and the advantage of beer-dregs with just a little sugar is due to the mild yeast-like odour of slow fermentation, which may fail if formalin be the insecticide ingredient. The handiest and safest preparation of fly-poison is that sold in the form of a dry flypaper, which is said to contain arsenic as the deadly ingredient. A very small piece of one of the sheets ordinarily sold should be placed on the summit of an inverted saucer; a mere spoonful of water now and then will suffice to moisten the same; there is little or no advantage in sprinkling a little sugar thereon, unless beer-dregs are added. This plan of using moistened poison paper is clean; it is safer than using a more fluid bait, and the ingredient is certainly efficient; the slightest taste thereof by an inquisitive fly ensures its speedy death. Another poison which has been recommended is a strong decoction of tea-leaves, to which a little sugar and beer may perhaps be added. It is said that the smell of geraniums is odious to the house-fly, and so pots of these plants may be grown beneficially on window-sills. Certain other odours and scents are believed to be likewise more or less fly deterrent, but their use is not effective warfare against fly propagation. Paraffin painted on window-sills is said to be very efficient.