Tuesday, July 19, 2011
Hilltopping = barhopping for butterflies
Amorous swallowtails head for the hills--literally--to find mates. This activity, known by the descriptive and delightful name "hilltopping," is shared by some other insect species. (But at least one species of swallowtail, the western tiger, tends to prefer trees that border rivers or even streets.) The males patrol the area, seeking females of their own species. When a female seductively flutters by, the male pursues her. They mate by pressing the tips of their abdomens together as he transfers a packet of sperm called a spermatophore to her.
When she is ready to lay eggs, she seeks an appropriate food plant for her species, confirming its identity with hairlike taste organs on the tips of her forelegs. After depositing 150 or more single eggs, she lives only a short time. Like most butterflies, a swallowtail lives fast, dies within a month of emerging from its chrysalis, and leaves a good-looking corpse.