Among alfalfa pests in Iran, Green pea aphid is gaining importance in recent years. This aphid had been collected in Karaj, Tehran, Shiraz, Isfahan, Kermanshah, Hamedan, Tabriz, Mashhad, Sanandaj, Zahedan and Kerman on alfalfa. Also it may be found in other alfalfa plaiting areas of Iran. Eastop (5) has reported, That the green pea aphid reproduces by parthenogenesis all the years with mild winters, while under cool condition it produces sexual forms (oviparous females and males) in the fall. Results of our observation showed that, The green pea aphid reproduces byrt1rne- sis, so that mQst of the year, only females are present. Our investigations showed that, onefemale reproduces 26-71 youngs (under condition 28-30°C maximum and relative humidity 57-58 percent). The time requred from birth to maturity takes 6-8 days. The green pea aphid can be observed all along the growing season with higher density from late may to mid June at Karaj area. During these periods, the mean monthly maximum temperature, was about 28°C and relative humidity about 60-65 percent.
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