Morphology and life cycle of alfalfa root scale Porphyrophora medicaginis (Hom.: Margarodidae) in East Azarbaijan

Morphology and life cycle of alfalfa root scale was studied in the field for 2 years from 2003. Alfalfa field was sampled weekly and biology of different nymphal instars was studied in field condition. The cysts were transferred to laboratory and their morphology and biology were studied. The field’s soil was sampled from depth 0-10cm and 10-30cm and its structure, pH and food materials were measured. The scale samples were sent to Plant Protection Research Institute for identeficacion. The investigations showed that this pest owervinters in field condition as first instar nymph (crawler). From mid-winter it transferred to cyst stage. Nymphs feed on the roots of the host until first week of Augest until adult females appear. The female produced an egg sac and laid eggs at a depth of 15 cm of the soil. The eggs hatched from mid-September and the crawlers appeared in the field. The adult males appeared from early September and this scale produced only one generation in a year.