The morphs of green apple aphid occurring on apple host in Himachal Pradesh, which is the main apple growing state of India, were ascertained and their life history was studied on the apple nursery plants from 2002 to 2006 in Mashobra locality (3101'N latitude, 7701'E longitude and altitude 2286 m above sea level) of Shimla district and Ner Chowk locality (31032'N latitude, 76054'E longitude and altitude 878 m above sea level) of Mandi district of Himachal Pradesh. Only two kinds of parthenogenetic morphs i.e. apterous and alate parthenogenetic viviparous females occur in this state. Biological characteristics, life history and behaviour of these morphs were studied in different seasons Heavy infestations of green apple aphid prevent the terminal growth of the plants which show distorted growth. This aphid pest builds up big colonies on twigs, leaf petioles and the underside of the leaves. Its settling behaviour on apple plants allows accommodating large number of aphids in a small area on shoots and leaves. Maximum alate morphs were produced from May to August and number of alates was also more in crowded colonies. The alate aphids infest new plants and build up new colonies there. The populations of this insect pest increase in early May and reach high peaks in July. The effect of aphids’ feeding on the growth of nursery plants was also measured.
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