Biology Colorado potato beetle, Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae)

Colorado potato beetle is the most important and dangerous pest of potato plant. Because، adults and larvae feed on stem، leaf and flower of potato a lot. Determination of biology of this pest in per region is necessary for selection of different control methods and their use time in integrated pest management. In order to، biology of this pest is studied in natural condition and 27±4 C temperature on surrounded potato vases. This insect overwinter as adult in soil. Adult insects after emerging mated and laid eggs in groups of 4- 76 in lower level of potato leaves. The eggs were hatched after four until five days. First instars larvae feed on potato leaves in communal، then feed median and margin of leaf. Upper instars larvae feed more، relation to lower instars larvae. Adult insects feed more relation to larval different instars. The medium larval period per instar took 2. 1 ± 0. 308، 2. 35 ± 0. 4، 3. 15± 0. 366 and 6. 95± 0. 826 days respectively. The medium total of larval period took 14. 55 ± 1. 146 days. This pest feed on potato leafs more، in per larval instars relation to before larval instars. Complete larvae ceased feeding and pupate in 3 centimeter depth of soil. Pupa period took 6-8 days. Colorado potato beetle has two generation in per year.