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Butterflies and Moths
By Robert T. Mitchell, Herbert S. Zim, Andre Durenceau
St. Martin's PressCopyright © 2002 St. Martin's Press
All rights reserved.
Butterflies and moths are most numerous in the tropics, but temperate areas have a bountiful supply of many species. Like all insects, they have three main body regions (head, thorax, and abdomen), three pairs of jointed legs, and one pair of antennae. Most have two pairs of wings. A few are wingless.
Insects that possess certain basic structures in common are classified into large groups or orders. Butterflies and moths are members of the order Lepidoptera, derived from the Greek lepidos for scales and ptera for wings. Their scaled wings distinguish them as a group from all other insects. When butterflies and moths are handled, the scales rub off as colored powder. Under a microscope, the colors and forms of the scales are amazing.
Lepidoptera is the largest order of insects next to Coleoptera (beetles). Beetles are estimated at about 280,000 species; Lepidoptera at 120,000, with about 14,000 species in North America. Lepidoptera is usually divided into three suborders: first, Jugatae, with about 250 primitive species that somewhat resemble caddis-flies; second, Frenatae, most moths; and, third, Rhopalocera, the butterflies, including true butterflies and skippers.
The suborder Rhopalocera is divided into two super-families: Papilionoidea, which includes 19 families of true butterflies, and Hesperioidea, two families of skippers. Butterflies and skippers are easy to distinguish by the shape and position of their antennae (here and here).
The suborder Frenatae includes about fifty families of North American moths. No single feature will enable one to tell a moth from a butterfly or skipper, but a frenulum on the hindwing of most moths extends to the forewing, holding the wings together. The presence and position of simple eyes (ocelli) and leg spines, the nature of the antennae, and the shape and vein pattern of the wings are used in moth identification. To make veins more visible for study, the wings can be moistened with alcohol.
SCALES cover the wings of all Lepidoptera in overlapping rows. Moth scales are variable, sometimes "hairy." Butterfly scales are more uniform. Some, on males, are modified into scent scales.
This guide employs the common names of butterflies and moths for ease of use by beginners. But the book closely follows scientific classification of Lepidoptera. The 6 families of North American butterflies as herein named are those recognized in the collection of the National Museum of Natural History at the Smithsonian. They are broken down into genera (plural of genus), which in turn contain one or more species. To help you follow the organization, butterfly family names appear in red, butterfly genera and species names in black. Because they are so numerous, moths are dealt with mainly on the family and species levels.
Each species of Lepidoptera bears a double scientific name, such as Pieris rapae for the Cabbage White. Pieris is the name of the genus; rapae is the species name. See here for scientific names of species illustrated in this book.
LIFE HISTORIES Lepidoptera develop by a complete metamorphosis, which is characterized by four distinct growth stages, as shown for the Gypsy Moth. The egg hatches into a larva, or caterpillar, which grows and molts (sheds its skin) several times before transforming into a pupa from which a winged (usually) adult emerges later.
EGGS of Lepidoptera vary greatly in size and shape. Many are spherical but some kinds are flattened, conical, spindle- or barrel-shaped. Some eggs are smooth, but others are ornamented with ribs, pits, or grooves, or networks of fine ridges. Each egg has a small hole through which it is fertilized.
The adult female may lay eggs singly, in small clusters, or in one egg mass. Most often eggs are deposited on a plant that will serve as food for the larvae. Some eggs are laid on the ground, and the newly hatched larvae must seek their food plants. Eggs laid during the summer are usually thin-coated; those that overwinter before hatching have a thicker outer coat and are sometimes covered by "hair" from the moth. They may also be covered with a foamy layer, as shown for the Tent Caterpillar.
Most eggs hatch in a few days. The larva, which can frequently be seen inside the egg just before hatching, eats its way out and sometimes also eats the eggshell.
LARVAE of Lepidoptera are caterpillars, though some are known as worms, slugs, or borers. North American caterpillars range in length from 0.2 inch to about 6 inches. Like the adult, the caterpillar has three body regions — head, thorax, and abdomen.
On each side of the head are tiny ocelli, or simple eyes, usually in a semi-circle, and a tiny antenna. The mouthparts include an upper lip (labrum), a pair of strong jaws (mandibles), two small sensory organs (palpi), and a lower lip (labium), which bears a pair of spinnerets, used for spinning silk threads.
On each of the three segments of the thorax is a pair of short jointed legs, ending in claws. On each side of the first thoracic segment is a spiracle, an opening for breathing.
The abdomen, usually composed of ten segments, bears two to five pairs of short, fleshy prolegs. Segment 10 bears the largest pair, the anal prolegs. Spiracles occur on each side of the first eight abdominal segments.
Most larvae feed actively throughout their lives. Some kinds mature in a few weeks, others in months. Some become dormant, or estivate, during the summer; others hibernate, overwintering in newly hatched, partly grown, or fully grown stages. Most kinds feed on leaves, but others feed on flowers, fruits, and seeds, or bore into stems and wood. A few species are scavengers and a small number prey on insects, especially plant lice. A few feed on animal products like wool, silk, or feathers.
As a larva grows, it sheds its skin, or molts, allowing for another growth period. Larvae in stages between molts are called instars. Early instars may differ from later ones in color, markings, and shape.
Caterpillars with horns and spines may appear treacherous, but only a few, such as the lo, Hag Moth, Puss Moth, Saddleback Caterpillar and related "slugs," have irritating spines or hairs to avoid.
PUPAE are the resting forms in which the larvae transform into adults. Most butterflies and moths in temperate regions spend the winter as pupae, though the pupal stage of some species lasts for only a few days or weeks. In a prepupal stage the caterpillar loses its prolegs; later its mouthparts change from chewing mandibles to a long tongue (if present in the adult), wings develop, and reproductive organs form. External factors such as temperature and moisture may trigger the changes, but the actual transformation is caused by hormones.
A butterfly caterpillar, when mature, attaches itself to a firm support before changing to a naked pupa, known as a chrysalis. Caterpillars of swallowtails, sulphurs, and whites deftly support theirs with a strong silk thread.
Most moth larvae, when full grown, burrow into the ground and pupate there in earthen cells. Others pupate amid dead leaves or debris on the ground, in hollow stems or decaying wood, sometimes with material drawn loosely together with silk. Hairy species usually mix their hairs with silk, making a flimsy cocoon. Silk Moth larvae spin tough papery silken cocoons that house their pupae. When emerging from these tight cocoons, moths secrete a fluid that softens the silk. Bagworm Moths construct cocoons around their bodies as they grow. At maturity they fasten the finished cocoons to twigs with silk.
While butterflies emerge easily from chrysalises, moths often exert great effort to break through cocoons or push their way up through the ground. Both emerge with soft small wings with miniature wing patterns. As fluids are pumped through the veins, the wings expand. Later the veins harden, providing a rigid support for the wing membrane.
ADULT butterflies and moths have a pair of segmented antennae and a pair of large, rounded compound eyes on their heads. Many moths also have a pair of simple eyes. Butterflies and many moths have a coiled tongue (also called a proboscis), which unrolls into a long sucking tube through which the adult feeds on nectar and other fluids. This tube may be as long as the adult's body.
Each of the three segments of the thorax bears a pair of five-jointed legs. Some groups of butterflies have the first pair of legs reduced, and females of the Bagworm Moth have no legs. A pair of membranous wings are attached to the 2nd and 3rd thoracic segments of most butterflies and moths but a few kinds are wingless. The vein pattern of wings is used in classification.
At the end of the ten-segmented abdomen are the sex organs. They are used in the accurate identification of many species. The female's abdomen is usually larger than the male's. The latter can be distinguished by the claspers of the sex organs which protrude as plate-like structures at the end of the last segment.
NATURAL ENEMIES of Lepidoptera abound. Various insects feed on them. So do spiders, birds, rodents, reptiles, amphibians, and night prowlers like skunks and raccoons. Parasitic insects lay eggs in and on caterpillars, eggs, or pupae, which then become food for the parasitic larvae. Bacteria, fungi, protozoa, and viruses cause diseases; unfavorable weather also takes its toll.
DEFENSES against such a host of destructive forces are necessary for survival. The capacity of females to lay hundreds of eggs is one. Camouflage, hiding from predators, is another. Other protective features are body markings that frighten enemies, and hairs, spines, or body juices unpleasant to them.
MAN is enemy no. 1. The destruction of favorable habitat from land development has led to a great decline in their numbers. Herbicides and pesticides kill them. Floodlights at malls, intersections, and athletic fields are lethal moth traps. Against man, they have no built-in defenses. For their survival, they are becoming more dependent on people who care, and so become involved in conservation.
CONSERVATION is of growing importance. At least two species of butterflies are now extinct, and a number of other Lepidoptera have been listed as Threatened or Endangered. Here are some ways that you can help.
ORGANIZATIONS devoted to the study and conservation of butterflies and moths can provide information about the butterflies and moths in your area. Many states have programs that collect information about plant and animal life and make proposals for species of special concern. Contact your state office or the Nature Conservancy about local efforts where you can be helpful. Some national organizations to consider are:
North American Butterfly Association, Inc. (NABA), 4 Delaware Road, Morristown, NJ 07960; http://www.naba.org/, is the largest organization in North America working to increase public enjoyment and conservation of butterflies.
The Xerces Society, 4828 SE Hawthorne Blvd., Portland, OR 97215-3252; (503) 232-6639; http://www.xerces.org/, is an international organization focused on public education and conservation of invertebrates.
Lepidopterists' Society, 9417 Carvalho Court, Bakersfield, CA 93311; http://www.furman.edu/, is an international organization devoted to the study of butterflies and moths. Publications include the News of the Lepidopterists' Society and the Journal of the Lepidopterists' Society.
The Nature Conservancy, 4245 N. Fairfax Drive, Suite 100, Arlington, VA 22203; http://nature.org/, is the largest private international conservation group dedicated to preserving natural communities by protecting lands and waters.
CREATE A BUTTERFLY GARDEN Plant such perennials as pussy willows, lilac, blueberry, Clethra, phlox, butterfly weed and butterfly bush, lantana, and such annuals as zinnia, French marigold, and single petunia in your garden to provide butterfly food throughout the season. Also plant appropriate food for larvae of the butterflies that come to feed as indicated in this book.
REAR butterflies and moths from eggs or larvae for release. Watch them grow and develop. See how they move, how they feed, what they do. Then return them to their preferred habitat.
Female moths confined in paper bags will often lay eggs there, but butterfly eggs are harder to obtain. Look for them when you see a butterfly exploring the leaves rather than the blossoms of a plant. Chewed or missing leaves on a plant are clues to the presence of caterpillars nearby that you might collect for rearing.
Eggs and small larvae at first can be kept in tightly sealed, clear polyethylene sandwich bags, together with a few leaves of their plant food. Keep each kind in a separate bag. Keep the bags out of the sun or excessive heat. Remove the larval droppings every day or so. Reverse the bag and add fresh leaves whenever the old ones start to yellow or to dry out. Use leaves of the same species of plant, and do not bag them when they are wet.
Transfer 2-inch larvae to larger clear bags or to tightly sealed cans, such as 1-lb coffee cans. To watch developments, the "bouquet" set-up can be used (see the illustration).
When a butterfly larva is almost full grown, put a stick in the can or bag to encourage the larva to form its chrysalis on it.
Large numbers of lateinstar larvae of the same species and age can be reared in big freezer bags containing branches of the food plant, as illustrated. To clean out droppings, untie and allow them to fall through the opening.
Large numbers of larvae can be reared outdoors with less care by enclosing them in a strong net bag pulled over the end of a growing branch of a tree or bush and tied securely farther down the branch.
Caterpillars that make cocoons, such as Silk Moths and Tiger Moths, can be reared like those of butterflies. However, the larvae of Regal Moths and most noctuids must be given a few inches of damp (not wet) sterile soil or peat moss into which to burrow when full grown. The resulting pupae can be overwintered in sealed plastic sandwich bags (along with the damp medium) in a refrigerator. Keep overwintering cocoons and chrysalises outdoors, in cages to protect them from predators.
Adults emerging from pupae in the following seasons must be given ample room for spreading their wings and a rough surface for climbing to a perch. For chrysalises and cocoons only, a screened cage is needed. It can be made from a rolled section of wire screening or small-mesh hardware cloth; use paper plates for top and bottom.
A cylindrical cardboard rolled-oats box makes an ideal emergence cage for cocoons and chrysalises. When the open top is covered with a nylon stocking (held in place by tucking the leg and toe under a loop of material near the rim), the adult can be captured and brought to hand by extending the leg above the open top as the adult flies into the leg trying to escape.
Keep pupa formed in soil cans with a rough surface for climbing. Cover the top of the can with a piece of clear plastic to keep the soil from drying out and to let you see any emerging moths.
After you have completed your observations, return the adults to their preferred habitat.
COLLECT SPARINGLY and follow laws concerning endangered species. Usually, adults are collected while feeding at flowers or bait. The specimen is quickly transferred to a killing jar. Later it is mounted, spread, labeled, and catalogued. Equipment items can be purchased from a biological supply house, such as:
American Biological Supply Co, 2405 N.W. 66th Court, Gainesville, FL 32653-1633, 352-377-3299, Fax: 352-375-AMBI.
BioQuip Products, 17803 La Salle Avenue, Gardena, CA 90248-3602, http://www.bioquip.com/, e-mail: firstname.lastname@example.org/
Carolina Biological Supply Company, 2700 York Road, Burlington, NC 27215, http://www.carolina.com/
Insect Lore, Box 1535, Shatter, CA 93263, 1-800-LIVE BUG (1-800-548- 3284), http://www.insectlore.com/
Ward's Natural Science Establishment, 5100 West Henrietta Road, P.O. Box 92912, Rochester, NY 14692, http://www.wardsci.com/
COLLECTING NETS should be lightweight, with rim 12 to 15 inches in diameter. Strong nylon net bag should be 27 to 32 inches deep, roughly funnel-shaped but not sharply pointed at the end.
KILLING JARS should have wide mouths and seal tightly. Put enough paper toweling in the bottom to absorb a teaspoon to a tablespoon of liquid. To use, add enough ethyl acetate or carbon tetrachloride to saturate the paper; pour off any excess. Specimens too stiff for mounting can be relaxed by enclosing for a few hours in a plastic food storage box on a sheet of plastic spread over water-saturated paper toweling.
SPREADING BOARDS are made of soft wood with a center channel in which the body of the specimen fits. When specimen is relaxed, insert insect pin straight down through center of thorax, ¼-inch from head; then stick pin into center of channel until wings are level with upper surface of board. If necessary, brace by inserting a pin in the channel on each side of specimen's body at base of hindwings. Spread wings gently with foreceps and pins so edges of forewings are at right angles to body and hindwings are in a normal position. Pin wings in place with paper strips. Neatly position antennae. Allow several days for drying.
Excerpted from Butterflies and Moths by Robert T. Mitchell, Herbert S. Zim, Andre Durenceau. Copyright © 2002 St. Martin's Press. Excerpted by permission of St. Martin's Press.
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