The Buckeye occurs at all our sites but is non-resident above 5000'. At Lang it has overwintered successfully, but clearly not every year. It is not certain that it ever overwinters at Sierra Valley. In some years, e.g. 2005, there are massive waves of immigrants in early summer. We do not know where they come from. In such years the peak density may be reached in midsummer, as Buckeye reproduction temporarily outstrips the capacity of natural enemies to control the population. The Buckeye breeds continuously in warm weather. Usually the population peaks in autumn.