There are nearly two hundred species of horse flies in North America, and this creature represents one of the commonest forms. It doubtless hatched out somewhere on the edge of the brook which flows through my place in Maryland, and its larval self fed upon other insect larvæ or on the snails and slugs it found itself among. The bands of iridescent green and copper and purple across its enormous eyes made it a beautiful creature to look upon. We never used to think the bite of flies was anything worse than annoying, but recently, since we have discovered the danger of letting the germs of disease into the blood streams of our bodies, we have come to see the ghastly possibilities which lie in the piercing mouthparts of these flies. They suck the blood of animals whose blood streams may be swarming with disease germs, and then fly directly to our houses and puncture our skins with a beak covered with these germs which slip off into our veins. Until we know that the diseases of the birds, and field mice, the coons and 'possums, and all other warm-blooded beasts of a locality are harmless to us, or that it is impossible to transmit them to human beings, it is best to look upon these blood-sucking creatures as winged hypodermic syringes laden with disease. It has been suggested that the horse flies carry anthrax, and their bites sometimes cause malignant pustules. They are also under suspicion as carriers of infantile paralysis. FEATHERED INSECTS (_Lepidoptera_) These are peculiarly the feathered fliers of the insect world, for their wings and their bodies, too, are covered with most remarkable one-celled feathers or scales of gorgeous colors which make of some of them the most brilliant of all living things. Just what these scales are for is not entirely clear, and will not be, perhaps, until we understand the purpose of the gorgeous coloring itself. There is a theory that these scales help to grip the air in flying. It is a curious coincidence that one of these gorgeously colored creatures should furnish mankind with the material for his own most gaily colored raiment. The silkworm is one of the very few domesticated insects, so to speak, of all the hundreds of thousands of insect species in existence, and a hundred millions of dollars is paid every year for the delicate silk threads unraveled from countless millions of cocoons which the silkworm larvæ have laboriously fashioned around themselves. To many people, moths are known by what they leave behind--holes in the winter woolens; and butterflies are to them, somehow, things of the sunlight and the summertime. It is worth while to know that these great families of butterflies and moths are not by any means divided equally, that for every family of butterflies there are at least nine of the moths and that the butterflies form but a small proportion of the gaily colored insects of the fields.