Overwintering survival of Aphthona beetles (Coleoptera: Chrysomelidae): a biological control agent of leafy spurge released in North Dakota.

We evaluated the effects of snow cover and debris cover on overwintering success of Aphthona from 2001 to 2004 in southeast North Dakota. Chill degree-days, soil temperature, and duration of soil temperatures were monitored in field plots. Emergence of Aphthona from soil cores collected in October and held in the laboratory under simulated winter conditions did not differ across treatments.