-
1. Understanding the Butterfly
- Texas A&M University Press
- Chapter
- Additional Information
1 Understanding the Butterfly l Butterflies, along with moths, are easily differentiated from all other insects. They belong to the order Lepidoptera, a name composed of two Greek words, lepis meaning “scale” and ptera meaning “wing,” combined to mean “scale-winged,” which aptly describes their most obvious feature. The wings, as well as the body, are almost always entirely covered with scales. Scales on the wings are usually flat, but the scales covering the body are often long and silky, appearing almost hairlike. In most respects butterflies and moths are quite similar, but four characteristics usually separate them. In almost all species of butter flies, the antennae end in a club or swelling at the tip, while the antennae of moths are slender or feathery but rarely clubbed. Also, butterflies generally fly during the day, while moths fly primarily at night. However, there are numerous exceptions to the generality concerning moths, since many fly about during the day. Another defining characteristic is that butterflies usually rest with their wings closed and held vertically over the back. Exceptions to this occur during periods of basking when the wings of most species may be spread flat, and the Skippers frequently rest with their wings half spread. Conversely, most moths rest with their wings outstretched and held flat against the surface on which they are resting or drawn back tightly along the sides of the body. Last, and as a general rule, butterflies more often form an unprotected chrysalis in the open, while moths form a tough, silken cocoon in which to pupate. Life Cycle In their life cycle, butterflies go through four distinct stages, together known as a complete metamorphosis. These stages of growth are 2 l chapter 1 Janais Patch (Chlosyne janais) the embryo stage (egg or ovum), the wormlike growing stage (caterpillar or larva), the mummylike transition stage (chrysalis or pupa), and the winged reproductive stage (adult or imago). Adult females usually lay eggs on or near the food plant that will sustain the caterpillars or larvae upon hatching. The eggs are almost always left unattended and will usually hatch in a few days. In some species eggs are left to overwinter, and in some rare cases they will not hatch for two years or more. Eggs are very soft when first laid and are usually attached firmly to the food source with a sticky, gluelike substance. Slowly, the egg takes on its particular form and color as the shell dries and hardens. Shape is usually characteristic for the species, and under magnification each egg reveals its own beautiful markings and coloring. It may be round, domed, flattened, elongated, or shaped like a minute barrel, urn, pincushion, spindle, or sea urchin. The egg surface may be pearly smooth or elaborately sculptured with raised or sunken ribbing, horizontal furrows, pits, grooves, knots, spikes, or other ornamentations. Eggs of the Cabbage White (Pieris rapae) are fat yellow cones with intricate lengthwise striations . The Pipevine Swallowtail (Battus philenor ) lays large, reddish-brown, almost perfectly spherical eggs, while eggs of the Guava Skipper (Phocides polybius lilea) resemble beautifully ribbed and flattened turbans. Eggs of the Blue Metalmark (Lasaia sula) resemble two pies, one stacked on top of the other. Females of each species instinctively choose the exact food plant on which to deposit their eggs, using an intricate detection system that involves sight, feel, taste, and smell. Many butterflies lay their eggs singly, but others attach several in a single layer or in clusters of up to five hundred, usually to the underside of a leaf. Depending on the species, a female may lay between one hundred and two thousand eggs during her lifetime. Immediately upon hatching, the young caterpillar usually eats all or a portion of the eggshell as its first meal, thus gaining vital nutrients that have been passed on from the mother. With many species the eating of the shell is extremely important, for the young larvae will not survive if they do not do so. The caterpillar then begins feeding on the leaf or flower it is on. In this nutritive stage of the larva’s life, its entire purpose is to eat—and eat it does. As it grows, it ravenously consumes food at an astonishing rate. By the time the larva has finally become satiated, it may have increased its weight by as much as one thousand times. Some caterpillars, such as those of the Clouded Sulphur (Colias...