Phenology of Egg Hatching for the Red Turnip Beetle, Entomoscelis americana (Coleoptera: Chrysomelidae) 1

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Abstract
The phenology of egg hatching for the red turnip beetle, Entomoscelis americana Brown, was studied at five constant temperatures (5 to 20°C) in the laboratory and in the field during 4 years. The threshold for hatching was near 5°C, and the upper limit was near 37.5°C. After diapause development was completed, hatching occurred quickly at temperatures above 5°C and was completed after 2 to 18 days at 20 to 7.5°C in the laboratory. Hatching was initiated within 2 to 16 days and completed within 2 to 5 weeks after snow melt in the field. A logistic equation of the form 1/Y = K/1 + e,a−bx (Y. mean hatching time; x , temperature; K , a , and b , constants, accurately described the relationship between temperature and the mean time to hatch in postdiapause eggs in the laboratory. A computer simulation model, which uses the logit equation P = 100/1 + e−(a+bx)( P , percent hatch; t , time; a and b , constants) and predicts hatching in nature, is described. This model predicted the time of hatching in the field to within 1 day in 3 of the 4 years. In the fourth year, the predicted time of hatching was 7 to 9 days earlier than the observed. The ecological significance of the data is discussed.