Annual counts of eastern yellowjacket,Vespula maculifrons(Buysson), colonies in a Delaware woodlot in 1965–82 exhibited a statistically significant, 2-yr cycle of abundance. In 1976–80 the mean size of queen cells also exhibited an apparent 2-yr cycle. When queen cell size was up, colony abundance was down and vice versa. This is the first quantitative evidence of variation in a queen characteristic that may be linked to the familiar cycles of yellowjacket abundance.