Complementary investigation on life cycle of Ennomos quercinaria (Lep.: Geometridae) in Mazandaran province

August thorn, Ennomos quercinaria (Lep.: Geometridae) has been recognized as an important defoliator of forest trees throughout the world. Several outbreaks have been observed in Mazandaran province during the last decade. Study on the biology of this pest in laboratory conditions revealed that it has six larval instars. Average larval longevity estimated as 46.16±3.74 days. Larvae are green to brown in color and pupate among folded leaves. The pupal period of males and females were 13.85±0.25 days and 12.44±0.16 days, respectively. Males had longer life span (7±0.44 days) compared with the females (5.76±0.25 days). Life cycle averaged 64.52±5.86 days. The flight period was recorded from May through late June. Agust thorn is a univoltine insect and overwinters as an egg among foliage of the host trees. In this study, six spiders, two beetles, three wasps and a fly were identified as natural enemies.