Cashew, Anacardium occidentale, an increasingly important cash crop in the coastal region of Tanganyika, is damaged by two widely distributed species of Helopeltis, H. anacardii Miller and Helopeltis sp.

At Bagamoyo, in June 1955, the period from egg to adult for H. anacardii occupied 35·9 days; that for Helopeltis sp. occupied 39·2 days.

Damage is caused to the leaves, shoots, buds, young fruits and to the cashew apple. Damage in a young tree is more marked than that in an old tree and may result in its being malformed or stunted.

The build-up of Helopeltis populations on cashew follows the main growth period of the crop which begins shortly after the end of the main rains in May. The insects are readily found from July to October-November, when the crop matures.

Application of a 0·5 per cent, γ BHC dust and a 5 per cent. DDT dust to two-year-old trees increased the amount of crop but the increase was not economic owing to the fact that the trees were coming into bearing for the first time. Cross-infestation from untreated plots may also have reduced the effectiveness of the treatments.

Three or four applications by a knapsack-type power duster of 0·5 per cent. γ BHC dust at 15-day intervals previous to flowering of the main crop gave promise of successful control in the field.