The Canadian Entomologist 126: 1263-1275 (1994) Temperature-dependent development of eggs, larvae, and pupae of the speckled green fruitworm, Orthosia hibisci Guenke, at constant temperatures of 5-30. 0°C, 7.5-27.S0C, and 0.8-20.g°C, respectively, was described. Development times decreased with increasing temperatures and minimum developmental times in eggs, larvae, and pupae occurred at ca. 27.5,25, and 20.8"C, respectively. Variation in development times of all life stages was modelled accurately (R2 values 0.98-0.99) with a Weibull distribution. Relationships between temperature and developmental rates of all life stages were described by linear degree-day (DD) and nonlinear poikilotherm models. There were significant differences (ANOVA, P < 0.05) among the slopes of regression equations THE CANADIAN ENTOMOLCK~~ST SeptemberIOctober 1994 61,3 degrks-jours au-dessus du seuil. Les taux de developpement des oeufs et de tous les stades larvaires pondkrks sont decrits au moyen de modkles B six variables qui peuvent Etre inhibees par des tempkratures trop basses ou trop hautes. Le dkveloppement des chrysalides rkpond B un modkle B quatre variables qui peuvent &tre inhibees par des tempkratures trop basses, mais pas par des temperatures trop hautes. Ces rksultats peuvent s'avkrer utiles dans l'klaboration d'un modkle phBnologique de contrble d'O. hibisci. [Traduit par la Redaction]