National Geographic : 1952 Aug
259 Paul A. Zahl Two Live Beetles Look at Beetle Pictures. One Crawls Across His Enlarged Portrait Larvae of the broad-necked root borer (upper) injure poplar, oak, and chestnut trees. The Colorado potato beetle (lower) did not begin to eat potatoes until the plant was introduced into the southern Rockies, his home. They sit on a page from the Field Book of Insects, by Frank E. Lutz, G. P. Putnam's Sons. each time my fingers came close, it would begin again. The covering letter from Dr. Fairchild ex plained that workmen had found this cater pillar in his tropical gardens at Coconut Grove, Florida. It was a larva of the sphinx moth (Sphecodina abbotii), and the glittering tail ornament, more or less typical of members of this species, is intended to frighten enemies. One scientist has described seeing an oriole, about to devour one of these grubs, dart away with a scream when the creature lifted its snakelike tail with the tubercle shining like an eye. Self-protection, the endless job of staying alive in a world full of hungry birds and ani mals, accounts for much of the brilliance and intricate design my color camera captured. In many cases, design and hue match the twig, leaf, or plant on which the insect lives; for, in general, the longest-lived bug is the one that is hardest to see. But even this rule has exceptions. The in- sect that is unpleasant to taste, or poisonous, or has a sting, may advertise itself in brilliant colors to warn potential enemies away. The bitter but beautiful queen butterfly is a good example (page 253). More palatable bugs, in turn, may imitate their sour or stinging cousins to scare away predators. There are flies that look like bees, and moths that look like wasps. Nature Uses Varied "Paints" Nature paints her insect colors in a variety of ways. Many of the lovely hues of some butterflies and moths are produced by the diffraction, or breaking up, of light by multi tudes of microscopic ridges on the tiny scales covering the wings. The gold color of the Cassida beetle comes from an extremely thin film of fluid under the skin, which also diffracts light. The green of some caterpillars is created by chlorophyll of the plants they eat, deposited in the digestive tract and blood.