The Hatching Period of Winter and Summer Populations of Thaumetopoea pityocampa (Lepidoptera: Notodontidae) in Bulgaria.

The dynamics of the larval emergence of the "summer form" and "winter form" of Thaumetopoea pityocampa was studied in the period July-October 2020 in laboratory conditions. The biological material was collected from two sampling sites - Sandanski in the western foothills of Prirn Mts. and Dobrostan on the northern slope of the Rhodopes Mts. The region of Sandanski is occupied by the winter form and the region of Dobrostan - by the summer form. The phenological calendars of the two populations of T. pityocampa were found to be in agreement with the known temperature thresholds of the species. The culmination of the larvae hatching of the winter form was in early October - well after midsummer heats, while the culmination of the summer forms was in early August and coincided with the hottest period. In both populations, however, the culmination of hatching occurred at average monthly maximum air temperatures of about 28°C. [ABSTRACT FROM AUTHOR]