Aphidoidea forms one of the most important group of phytophagous insects because of their polymorphism, host alternating-heteroecious behaviour, reproductive haibts and above all for their role as largest group of insect vectors of plant viruses. The Fauna of India and the adjacent countries in this group constitutes about 16% of the world fauna, including a large number of rare, endemic species. However, no consolidated account of Indian aphids was so far available and the present work was started in 1976 and has been so planned as to be published in several parts. The first part published in 1980, deals with an introductory chapter on Aphidoidea leading to the subfamily Chaitophorinae. The second part deals with the subfamily Lachninae and the third part deals with the subfamily Pemphiginae. This fourth part deals with the subfamily Hormaphidinae besides two other related subfamilies Phloemyzinae and Anoeciinae. The entire subfamily is expected to be covered in at least eight separate parts. Besides, taxonomic accounts, information on host plant association, association with ants, natural enemies of aphids, distribution etc., are also provided in these parts.