Oviposition and diapause behavior were compared among populations of Colorado potato beetle, Leptinotarsa decemlineata (Say), from six locations in 1994 and 1995. Locations ranged from Winnipeg, Manitoba (49° 49′ N), to Rosemount in east central Minnesota (44° 44′ N). Newly emerged first summer generation adults were held in field cages at each location for 7–14 d, then observed for 7 d in the laboratory for frequency of oviposition and frequency of burrowing behavior associated with diapause. Females from the Red River Valley seldom oviposited and although frequency of burrowing varied among locations it was independent of field and laboratory conditions. Under long-day laboratory conditions, 9–15% of females from east central Minnesota oviposited with frequency dependent on photoperiod experienced in the field, the critical photoperiod was 15.8 h. Under long-day laboratory conditions, 18–52% of beetles from east central Minnesota burrowed with frequency dependent on cumulative temperatures experienced in the field. Cool conditions were associated with higher frequencies of burrowing. Beetles from Rosemount exhibited identical responses under short-day and long-day laboratory conditions. In contrast, under short-day conditions, beetles from Big Lake did not oviposit and frequency of burrowing was not dependent on field conditions. We concluded that there is local geographic variation in Colorado potato beetle populations not only between the Red River Valley and east central Minnesota, but also among the different locations within these two areas.