of its time eating and growing. But its skin does not grow, and so the caterpillar sheds it and grows
a larger one. It repeats this process several times. After the caterpillar reaches its full size, it forms
a protective shell. Inside the shell, an amazing change occurs--the wormlike caterpillar becomes a beautiful butterfly. The shell then breaks open, and the adult butterfly comes out. The insect
expands its wings and soon flies off to find a mate and produce another generation of butterflies. Butterfly caterpillars have chewing mouthparts, which they use to eat leaves and other plant parts.
Some kinds of caterpillars are pests because they damage crops. One of the worst pests is the caterpillar of the cabbage butterfly. It feeds on cabbage, cauliflower, and related plants.
Adult butterflies may have sucking mouthparts. The adults feed mainly on nectar and do no harm.
In fact, they help pollinate flowers. Many flowers must have pollen from other blossoms of the same kind of flower to produce fruit and seeds. When a butterfly stops at a flower to drink nectar, grains
of pollen cling to its body. Some of the pollen grains rub off on the next blossom the butterfly visits. Kinds of butterflies
Scientists group the thousands of species of butterflies into families, according to various physical features the insects have in common. The chief families include (1) skippers; (2) blues, coppers, and
hairstreaks; (3) brush-footed butterflies; (4) sulphurs and whites; (5) metalmarks; (6) satyrs and wood nymphs; (7) swallowtails; (8) milkweed butterflies; and (9) snout butterflies. Each of these families has species in North America.
The life cycle of butterflies
The life of an adult butterfly centers on reproduction. The reproductive cycle begins with courtship,
in which the butterfly seeks a mate. If the courtship proves successful, mating occurs. Butterflies use both sight and smell in seeking mates. Either the male or the female may give signals, called cues,
of a certain kind or in a particular order. If a butterfly presents the wrong cue, or a series of cues in
the wrong sequence, it will be rejected.
In courtship involving visual cues, a butterfly reveals certain color patterns on its wings in a precise order. Many visual cues involve the reflection of ultraviolet light rays from a butterfly's wing scales. The cues are invisible to the human eye, but butterflies see them clearly. The visual cues help the insects distinguish between males and females and between members of different species.
Usually, a butterfly that presents an appropriate scent will be immediately accepted as a mate. The scent comes from chemicals, called pheromones, that are released from special wing scales. A
pheromone may attract a butterfly a great distance away. In most cases, the male butterfly dies soon after mating. The female goes off in search of a place to lay her eggs. She usually begins laying the eggs within a few hours after mating.
Every butterfly goes through four stages of development: (1) egg, (2) larva, (3) pupa, and (4) adult. This process of development through several forms is called metamorphosis.