Insect Pests

Abstract

IN connection with tropical agriculture, attention has been directed to the question of the influence of the condition of the host-plant on infestation with sucking insects. It is believed that such pests as thrips on cacao and froghopper blight on sugar-cane can be held in check by increasing the resistance of the plant by improving agricultural conditions. In the Agricultural News (vol. xix., No. 464) it is claimed that the “mosquito blight” of tea (caused by a capsid bug of the genus Helopeltis) is affected in a similar way, and that the condition of individual tea-bushes determines the susceptibility to attack. The distribu tion of mosquito blight appears to be connected with soil conditions, andanalytical data indicate that soils on which the pest is prevalent show sigillarities in the potash-phosphoric acid ratio, the addition of potash having an appreciable, though irregular, action in reducing the blight. Water-logging tends to encourage infestation, probably because the vitality of bushes grown on such areas is lowered; draining is the remedy advised in such cases. Acidity and poverty of soil are other factors which vitiate the health of the tea-bushes, so rendering them more liable to attack.