The seasonal biology of Dermacentor variabilis (Say) has Ьееп determined along the Atlantic Coast from southern Nova Scotia to northern Florida and inland to Indiana. This range, over 160 of latitude, includes both а difference о! 150 of теап annual temperature and а shift from oceanic to а continental climate. The infiuence of this shift in temperature regime оп the observed local periods of seasonal activity was correlated with the infiuence of теап temperature оп development rates of the life cycle stages, generation times, and species range.