Having examined all the wings we can find for the time being, we may turn our attention to mouths. The mouth parts of insects are not only interesting but important; one of the first things an economic entomologist does with a new specimen is to examine its mouth parts. The mouth will tell us what manner of feeder its owner may be. Some insects have sucking mouths, and they must feed perforce on liquids; others have biting mouths, and they are likely to do damage to crops by eating them. Then there are lancet-like mouths and mouths which are a compromise between biting and sucking ones. The subject, however, is somewhat complicated, and entails a knowledge of insect anatomy, so we will merely deal with a few easily understood examples. Our butterfly has a sucking mouth; it is known as a proboscis, and may be found, coiled like a watch spring, beneath its head. There is no trace of anything in this mouth capable of biting or even piercing the most delicate structure. The house-fly is also possessed of a proboscis though of different design. Though a dangerous, disease-carrying insect, it can do no harm with its mouth. The partiality of the house-fly for sugar is well known, and it is interesting to learn how, with its soft fleshy mouth, it can satisfy its cravings. Let us watch one at work on a lump of sugar through our pocket lens. If we look carefully we shall notice that the fly, as he thrusts his proboscis here and there, emits from it a little drop of liquid; after a momentary pause the liquid is sucked up again, it has dissolved a little of the sugar, and the fly enjoys the sugar-laden liquid. People frequently state that they have been bitten by a house-fly--a sheer impossibility. What really happens is that they mistake the very similar stable fly for the house-fly. If one of these insects be captured and examined, we shall find not the soft fleshy proboscis of the house-fly, but a cruel looking, awl-like mouth easily able to penetrate the human skin. Certain tropical flies, known as Pangonias, have such formidable and lengthy piercing mouths that they can penetrate thick clothing and puncture the skin below.