The earliest reference to the occurrence of Helopeltis in Ceylon was made by the French entomologist, Signoret (1858), when he described Helopeltis antonii, the so-called “Mosquito Blight”. Helopeltis attacking cacao in Ceylon was first recorded in the year 1880 or 1881 in the Matale district (Green, 1901), the damage to the young leaves and stems having attracted the attention of cacao planters. Populations of Helopeltis occurring on cacao today, however, favour the pods, damage to young leaves and stems being relatively rare and generally associated with poor shade over the cacao plant. This apparent change of feeding habits prompted a careful and critical examination of the existing species of Helopeltis in Ceylon. Extensive collections of Helopeltis from the major cacao-growing areas in the island, including the Matale district, have not provided any specimens referable to Helopeltis antonii. The new species described below was the only species of Helopeltis found on cacao at Teldeniya, Kundasale and in the Matale district, which may be regarded as representative of the major cacao-growing areas of Ceylon.