Is the winter survival area of Empoasca fabae continuously expanding?

1. Empoasca fabae is a migratory pest that overwinters in the Southeastern United States (US) and damages crops throughout its summer range in North America. Its spring arrival has advanced by 9.7 days between 1951 and 2012, and increased damage is linked to warmer conditions that accelerate host and pest development. Yet whether this advance is also associated with a northward expansion of its winter survival area remains an open question. 2. Here, we analyzed 126 years of minimum temperature data across the contiguous US to address this question. Using its winter survival threshold (-9{degrees}C), we calculated the annual winter survival area for E. fabae (temperature-only) and tested for