Psyche casta Pallas is a moth and member of the family Psychidae. It was introduced into North America at the beginning of this century, and has spread rapidly in northeastern US. The life history and natural history of P. casta are described. Food preferences of the caterpillars were tested for in Michigan. The most preferred food was a mix of four species of crustose lichens, growing on wooden fence posts. A possible thermoregulatory function of the permanently inhabiting larval case was investigated. Temperatures within cases were almost always lower than ambient temperatures. In addition, caterpillars location and change of location throughout the day were not affected by the direction of the sun. It is suggested that the case allows the caterpillars to be less affected by ambient temperatures than caterpillars without cases. High ratio of females was found at emergence in the lab. Hypotheses regarding the causes for this ratio are discussed.