Butterflies and moths

StoryImage( ‘/Images/Story//Auto-img-117027711825184.jpg’, ‘Photo courtesy of http://www.ecy.wa.gov’, ‘According to Washington State Department of Agriculture, since the accidental introduction of the gypsy moth to the United States in 1869, they have spread to 19 states, the District of Columbia and parts of Canada. The first gypsy moth control program was initiated in Massachusetts in 1889. ‘);
StoryImage( ‘/Images/Story//Auto-img-117027652629065.jpg’, ‘Photo by Dr. Robert A. Hedeen’, ‘The Vine Sphinx Moth displays interesting geometrical patterns. ‘);

The butterflies and moths belong to the insect order Lepidoptera (lepido, scale; ptera, wing), which is one of the largest groups in the insect kingdom. Everyone is familiar with these common insects, as there are 11,000 known different species occurring in the United States and Canada.

The scales on the wings and the other parts of the body come off like particles of dust when a lepidopteron is handled. The scales are thickly packed on the insect and are overlaid similar to the shingles on a roof. Thus, the thick coating of scales offers protection, and when they are colored, they beautify the animal, making them expressions of art and objects of collectors.

I have often been asked how you may differentiate between a butterfly and a moth. Lepidoptera experts will point to differences in the venation of the wings and in other parts of the body, but there are a few simpler rules to make the distinction. Butterflies fly by day and moths by night; moths spin a silken cocoon. in which to pass the pupal or resting stage, and butterflies do not; butterflies hold their wings vertically over their backs when at rest, and moths hold them horizontally when not flying; the antennae or feelers of butterflies are long and have a knob-like structure at the tip, whereas the antennae of moths are threadlike or bushy without a knob at the tip.

Insects go through a developmental process known as metamorphosis (many forms). This process may be rather simple in the primitive forms and very complex in the more specialized bugs. For example, butterflies and moths, flies, ants, bees, wasps, beetles, and others undergo what is termed complete metamorphosis, in which the immature forms in no way resemble the adult. In complete metamorphosis, there are two distinct stages before adulthood is reached: the larva and the pupa. In butterflies and moths, the larval stage is called a caterpillar, and it in no way resembles the adult.

Adult lepidopterans have a long, coiled, hollow tube for mouthparts with which they suck nourishing nectar from plants while caterpillars have chewing mouthparts with which they voraciously devour a wide variety of plants and stored organic materials and cause great economic damage.

Caterpillars of moths are of much more economic importance than those of butterflies, although some butterfly caterpillars are of considerable importance. The following are just a very few of the destructive caterpillars we have to deal with almost on a daily basis:

Cabbage Butterfly: The caterpillar of this butterfly is probably the most injurious to agriculture than any other species of butterfly. The caterpillars are velvety green in color and so closely resemble the foliage they inhabit that they are difficult to distinguish. It is an introduced species from Europe that arrived in the U.S. in 1860 and quickly spread to all parts of the country.

Indian Meal Moth: This is a small, pinkish worm-like caterpillar that horrifies the housewife when she discovers them infesting a variety of foodstuffs in her pantry. The best way to eliminate them is to inspect and discard any food products in which they are found.

Pink Boll Worm: This caterpillar is the second most important insect attacking cotton (the boll weevil, a beetle, is No. 1). As indicated, it attacks the boll of the cotton plant and, if unchecked, may cause a loss of 50 percent of the crop.

Gypsy Moth: This is another introduced species from Europe, making its appearance in Massachusetts in 1869. Millions of dollars have been spent in an effort to control this defoliator of our forests. The female moth lays her eggs on the ground, and the resulting caterpillars make their way up the trunk of the tree to reach the leaves upon which to feed. Knowledgeable homeowners protect their trees by placing barriers of various sorts around the base of the tree to stymie the hungry larvae.

Corn Ear Worm: This is a serious pest as it is a cosmopolitan feeder. Corn, tomatoes and cotton are a few of the plants it relishes. When feeding on corn, the caterpillar enters the ear via the silks and feeds on the kernels near the tip of the cob. It burrows into tomatoes and into the bolls of cotton. When fresh corn on the cob is available in the market, almost all shoppers will pull back the husks to inspect the ear for this “worm.”

Though most of the lepidopterans add an aesthetic beauty to the natural world and cause mankind no harm, there are many whose larvae, or caterpillars, are of great economic importance.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

From the Jan. 31-Feb. 6, 2007, issue

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