Abstract

Cylas, formicarius Fabricius, commonly known as the sweet potato weevil, is a well known cosmopolitan insect, which causes serious damage to sweet potato (Ipomea batatas) both in the field and storage. The loss caused by this pest is very extensive all over the world and in India damage to the extent of 60 to 70% is not uncommon. In recent years the weevil has been found to cause serious damage to sweet potato at Coimbatore especially to some of the exotic varieties. The author took up a detailed study on the biology of this insect at Coimbatore especially on aspects like number and duration of larval instars, alternate host plants and incidence of the pest on different varieties of the sweet potato etc. This paper gives an account of these observations together with detailed morphological descriptions of early stages of the weevil.

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