Developmental velocities of European corn borer,Ostrinia nubilalis(Hübner), colonies collected at four geographically separate locations (Delaware, Iowa, Missouri, and North Dakota) were compared. Each colony was reared under five or six constant temperature regimes. Mean developmental times and standard deviations about the means were determined. Developmental velocities were used to formulate both linear and sigmoid developmental velocity equations. Because the sigmoid and linear functions exhibited similar fits to the data, the latter were used in a European corn borer phenology model that predicts the period of second generation oviposition. The resulting predicted oviposition periods are reported for model runs using developmental velocity equations generated for the four colonies. The resulting predictions suggest that developmental rates are similar among the four geographically separate European corn borer populations. For European corn borers reared at 32°C, however, developmental times and developmental threshold temperatures during the period of larval eclosion to adult emergence appeared different among the colonies.