. Elementary entomology. Entomology. lOO ELEMENTARY ENTOMOLOGY nymph has five converging, spinelike appendages at the tip of the abdomen. The dragon-flies are among the swiftest fliers, dart- ing here and there after small flies, and are impoitant enemies of mosquitoes. They have received many local names, such as darning needles, snake doctors, etc., with which are connected many curious superstitions of sewing up people's ears, bringing snakes to life, etc., of which they are of course entirely in- nocent. They are usually dark colored, though often brilliantly marked with metallic blue, gre
. Elementary entomology. Entomology. lOO ELEMENTARY ENTOMOLOGY nymph has five converging, spinelike appendages at the tip of the abdomen. The dragon-flies are among the swiftest fliers, dart- ing here and there after small flies, and are impoitant enemies of mosquitoes. They have received many local names, such as darning needles, snake doctors, etc., with which are connected many curious superstitions of sewing up people's ears, bringing snakes to life, etc., of which they are of course entirely in- nocent. They are usually dark colored, though often brilliantly marked with metallic blue, green, and red. The damsel-flies are more slender-bodied and fly lazily about. The eggs are laid in the water or fastened to aquatic plants. From them hatch the little long-legged nymphs which may be found browsing in the ooze and mud of any pond. Dark-colored, flat, and spiny, they are hardly distinguishable from the debris of the bottom. They have a peculiar underlip, remarkably extensile, with two .powerful hooks at the tip, which, when thrown for- ward from the head, grasps the un- suspecting prey. When drawn in, the labium covers the front of the face and gives the nymph an exceed- ingly comical appearance, with its large, shrewd eyes on either side. The nymphs of the damsel-flies breathe through the tracheal gills at. Fig. 130. A, part of two rows of respiratory folds from cuticular lining of rectum of dragon-fly nymph {^Esr/t/ni). The shaded parts are abundantly supplied with tracheal tubes, as shown at B, a small part of one leaflet highly magnified, showing many fine tra- cheal branches (Redrawn from Miall) the tip of the abdomen, but the dragon-fly nymphs have a peculiar way of drawing water into the rectum, whose walls are very thin and lined with numerous tra- chea, so that the air in the trachea is purified through the wall of the rectum as if it were a tracheal gill. The water from the rectum may be ejected forcibly, so as to drive the nymph suddenly for- ward. When
Size: 1147px × 2177px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1, booksubjectentomology, bookyear1912
