The galls that are caused by thrips have not yet received the attention they deserve. This is perfectly comprehensible, because the few thrips-galls found in Europe have a very simple structure. The leaves are partly rolled inwards and poorly developed, and in case of heavy infection there is a general wilting of the whole plant, so that it looks diseased, (Grevillius, 1910). The infection takes place when the tissues are as yet little differentiated. They remain in this stage, and the infected organs show the symptom of hypoplasia. The number of thrips-galls in the tropics of the old world is very large, particularly so in the Indo-Malay region, which has been best examined for galls. About one tenth of all zoocecidia are caused by these insects (Docters van Leeuwen-Reijnvaan, 1926). Some galls have a very simple structure, but others show a distinct tissue differentiation and also hyperplasia. Similar highly developed thrips-galls have also been found in Australia.