All hummingbirds fly very swiftly. You know how they go,--not straight like most birds, but darting one way and another so quickly they can hardly be seen. As they fly, their wings move so fast they look almost like little clouds, and we hear the low noise we call humming. Hummingbirds eat nothing but tiny insects, and the honey of flowers, which they suck up through their long bill. They take their food without alighting, for they can hold themselves still before a flower, with the wonderful wings, as long as they choose. The bill of a hummingbird is much longer than his head. It is something like a pair of tubes through which he can draw up the sweet juices he likes. The tongue is long too, and it can be pushed out far beyond the end of the bill. It looks like a stiff white thread. We have in the Eastern States but one species, the ruby-throat, but there are several in California. No bird is more charming than our common RUBY-THROATED HUMMINGBIRD. He is most often seen flitting about among the flowers. But now and then one may catch him sitting demurely on a dead twig, dressing his tiny feathers. This bird is all in green, with a brilliant ruby-colored throat, which looks like a gem as he darts about. His mate is in green also, but her throat is white. You would not think this pretty midget could be a fighter, but he is. When a hummingbird finds a vine full of sweet blossoms, or a bed of bright nasturtiums, or any good place to feed in, he claims the whole of it for himself. He tries to drive away every other hummingbird who comes near it. Sometimes two of them will carry on a quarrel over a honeysuckle vine for days. The hummingbird is the most pugnacious bird in America. If he were as big as a crow, he would be a terror to man and beast, for he is afraid of nothing. This spirited mite of a bird will even attack an eagle, who is big enough to eat him at a mouthful. He beats him too, for he comes down on top of his head, where the big, clumsy fellow cannot get at him. There he pecks and pulls out feathers till the eagle is glad to get out of his clutches. A hummingbird's nest is one of the prettiest things in the world. It is not much bigger than a walnut, and is made of soft plant down, usually of a yellowish gray color. Perhaps you don't see how plant down can be made to keep in shape, without twigs or grasses to hold it. If you could see the bird make it, you would understand at once. She brings her stuff in small mouthfuls, and works it into a solid mass by strong efforts with beak and feet. She pokes and prods each tiny bunch as she brings it, till she makes it all hold together. It is a sort of felt. Then the little worker covers the outside with bits of lichen picked off the trees, and held on, it is said, by cobwebs. This makes the nest look exactly like the branch it is on. So it is very hard to see.