Why are flies continually brushing themselves with their feet and legs?

Because by this means they rub off the dust, and clean their eyes, head, corslet, and wings, - and to enable them to do this, their foot closely resembles a currycomb. Thus, in the common blow-fly, there are two rounded combs, the inner surface of which is covered with down, to serve the double purpose of a fine brush, and to assist in forming a vacuum, when the creature walks on a glass, or on the ceiling of a room. In other flies, there are three such combs on each foot. The insects are pretty thickly covered with hair, and the serratures (or teeth) of the combs free them from entanglement and dust. Even the hairs on the legs themselves are similarly used; for, flies not only brush with the extremities of their feet, where the curious currycombs are situated, but use part of their legs in the same way, particularly for brushing one another. - Mr. Rennie, in Journal of the Royal Institution.

Why is the dogs'-bane so fatal to files ?

Because of the elasticity of the filaments of the plant, which close and catch the fly the instant the trunk is protruded to feed on the expanded blossom: the poor prisoner struggles till exhausted to death, the filaments then relax, and the body falls to the ground. The plant will at times be dusky from the number of imprisoned wretches.