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BUTTERFLIES AND MOTHS AS INSECTS Butterflies and moths belong to a group of invertebrate animals called insects, them­ selves members of a larger systematic grouping called the Arthropods. Insects are extremely varied both in terms of size and appearance but all the members of this group

share certain characteristics. Insects have an external skeleton made of a hardened proteinlike material called chitin and, more fundamentally, all adult insect bodies are divided into three distinct sections: the head, the thorax, and the abdomen. The head bears important sensory organs including the eyes and antennae as well as the mouthparts; the thorax carries three pairs of legs and the wings, of which there are two pairs visible in almost all cases; the abdomen, which is segmented, contains the reproduc- tive, excretory, and digestive systems. Like all insects, butterflies and moths have life cycles

The wings of a butterfly are covered with layers of tiny scales, arranged like roofing tiles. The scales are pigmented and produce the color we so admire, such as in this western tiger swallowtail (Pterourus rutulus).

Following page: At rest, the hindwings of the io moth are hidden by the forewings. When alarmed, however, these are spread to reveal startling eyespots, which have the effect of temporarily putting off would-be predators.

Resting on tree bark, this tulip tree beauty (Epimecis bortaria) is amazingly well camouflaged. Moths with such cryptic patterning are usually adept at positioning themselves for best effect.

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