The heart-leaved willows along many brooksides are found to bear at the tips of many of their branches, knob-like bodies which look like pine cones. (Fig. 49.) Now everybody knows that willows bear their seeds in catkins. Why, then, should so many brookside willows thrust these cones in our faces? On cutting one of the cones open, we learn the secret. A tiny colorless grub rolls helplessly out of a cell in the very centre of the cone. It is the young of a small gnat, scarcely larger than a mosquito, and known as a "gall gnat." The cone-shaped body on the willow branch is called a "pine-cone willow-gall." The little gray gnat comes out in the spring. Any one can collect the galls from the willows and keep them in some kind of cage in the house until the gnats come forth. [Illustration: _Fig. 49. Knob-like bodies resembling pine cones._] The pine-cone gall is an enlarged and deformed bud. The twig might have developed into a branch but for the presence of the little larva. The scales of the cone are the parts which under more favorable conditions would have been leaves. The brook-lover cannot afford to miss the pine-cone willow-galls. Wandering along the brookside in spring or early summer, one is surprised to find so many insect visitors darting about in the air. There are dragon-flies of many shapes, sizes and colors; dainty damsel-flies perch airily on reeds, their gleaming wings a-flutter in the sunshine; sometimes a nervous mud-wasp alights for a moment, and then up and away. The dragon-flies seem intent on coming as near to the water as possible without wetting their wings. They pay no heed to other visitors, yet how easily they escape the net of the would be collector! Let them alone. Their business is important if we would have a new generation of dragon-flies to delight the eye next year. The eggs of these creatures are left in the water and the young ones are aquatic. If you would know more of them, dip down into the stream in some sluggish bay. Dip deep and trail the net among the water plants. Besides dragon-fly nymphs there will be caddice-worm cases like tiny cob-houses, water-boatmen, back-swimmers, and giant water-bugs.[14] These are insects characteristic of still or sluggish water, and are found in spring and summer. [14] These and other forms found in still or slow flowing water are described and pictured in Leaflet No. XII, Life in an Aquarium. [Illustration: _Fig. 50. Water-striders have long, thin legs._] The insects which skip lightly over the surface of the water where the current is not too strong, are water-striders. (Fig. 50.) Some are short and stout, others slender-bodied; but all have long thin legs. Their color is nearly black. As they scurry about in the sunshine the delighted watcher will sometimes catch a glimpse of their reflections on the bottom. Six oval bits of shadow, outlined by rims of light; there is nothing else like it! Be sure you see it.