The work reported here analyzes the effects of temperature on host consumption and preference of eastern pine processionary caterpillar Thaumetopoea wilkinsoni (Lepidoptera: Notodontidae). Nest censuses were taken in the field and food choice tests were conducted in the laboratory. Two pine species (Pinus nigra and P. brutia) were considered. Caterpillars hatched on both pine species were collected and included in experiments that were conducted under 4 different temperature regimes (15, 20, 25, and 30 degrees C). Needles of both pine species were offered as food. Results showed that increasing the temperature caused an increase in the feeding amount of the caterpillars and also a blurring effect on preference. Early instar diet was found to have effects on late instar diet.