Attempts to develop artificial diets for the Colorado potato beetle, Leptinotarsa decemlineata (Say), have had limited success (Hsiao 1972; Krzymanska and Zwolinska-Sniatalowa 1980). Consequently, all available rearing methods require the use of fresh potato foliage (e.g., de Wilde 1957) and large greenhouse space over an extended period of time. We needed a rearing method that could produce batches of beetles < 1 week old and with synchronized emergence (± 3 days) from a small laboratory colony of < 100 pairs of adults. One method might have been to induce adult diapause and break it whenever sufficient numbers had accumulated for testing. Unfortunately, this method requires mature adults that have fed for 1–2 weeks. not her procedure used in rearing a number of insect species uses a period of low temperature storage. For example, 2nd instar Choristoneura fumiferana (Clem.) can be stored at 1°C for 4–8 months (Grisdale 1970). Wegorek (1959) suggested that the hatching of eggs of L. decemlineata could similarly be delayed by placing them at relatively low temperatures. Wegorek observed that the incubation period of the eggs in Poland could take < 8 days in warm weather but last as long as 19 days in periods of cool weather when the temperature fell below 15°C. The feasibility of using this temperature dependence for incubation in our rearing program was investigated.