OVIPOSITION STRATEGIES OF COCCINELLA-SEPTEMPUNCTATA (COL., COCCINELLIDAE)

In central Japan, females of Coccinella septempunctata brucki laid egg s preferably on the under side of metal cans, wood and other materials , and the walls of a concrete gutter in sunny grasslands with colonies of aphids, in winter and spring. These materials have a high thermal conductivity, and are warmed readily by solar radiation. The developme nt of eggs attached to these materials was accelerated by the heart fr om the materials. Most eggs attached to the upper surface of such mate rials did not hatch because they were either desiccated by direct sola r radiation or eaten by predators. The under surface of metals is heat ed on sunny days by solar radiation, and the eggs are protected from d esiccation and cannibalism. The shortening of incubation may be an ada ptation to the rapid growth of aphid populations in early spring, and may reduce the chance of cannibalism.