The course of diapause development under field conditions for diapausing larvae of Adoxophyes orana (F.v.R.) (Lepidoptera: Tortricidae) was investigated. Larvae of A. orana were collected during the winter and early spring from 1996 to1999 from peach and cherry trees in the area of Naousa in northern Greece. Each larva was placed individually in a plastic cylindrical cell with a piece of artificial diet at 20°C under long-day (16:8 L:D) or short-day photoperiods (8:16 L:D). Photoperiod had a significant influence on diapause development. Duration in days, from transfer from the orchard to the laboratory until first molt and pupation of larvae, was also significantly affected by sampling date. Photoperiodic sensitivity was no longer detected after late January. Short-day photoperiod maintained diapause for larvae sampled until late January. Thus, A. orana may complete diapause development in late January, but it will not break diapause until spring, when temperatures are sufficiently high to induce diapause break.