ENTOMOLOGY 29 I 



recently Naude (1934) has studied these insects in relation to veld 

 destruction and erosion. 



It is commonly accepted that the staple diet of most species 

 consists of wood, which these insects are able to digest through the 

 agency of symbiotic Protozoa in their guts. Some kinds, however, 

 have been known for a long time to store grass and other vegeta- 

 tion in special granaries partly for food, and partly to grow special 

 crops of fungi underground. Naude considers that in South Africa 

 grass provides much the largest part of their diet. Dividing ter- 

 mites first into two groups, the harvesters which feed mainly on 

 grass and the fungus-growers which for the most part grow their 

 own crops underground, he considers the damage done and the 

 means of control. He concludes that the harvesters take a severe 

 toll of the grass veld, particularly in drought conditions, but that 

 they respond well to baiting, which appears to give relief from 

 them. The grass-eating capacity of termites can be confirmed by 

 observations in many parts of the continent; for example in Nor- 

 thern Nigeria fields of sown grass may be completely consumed by 

 these insects in the course of a few days. The fungus-growers are 

 relatively easy to control, but tend to be vainly attacked by farmers 

 in the mistaken idea that they are responsible for the most serious 

 veld denudation. 



Even if wood is not the principal food, most termites will take to 

 it whenever occasion offers, and this has led to endless expense in 

 making buildings termite-proof and in substituting metal for wood 

 as material for railway sleepers. A problem of growing importance 

 is the damage done by these insects to landing-grounds for aero- 

 planes. Some species work rapidly in throwing up their mounds 

 or termitaria and accordingly heavy expenditure on labour is 

 necessary to keep aerodromes in condition. 



Sericulture 



Though not connected with pests or diseases, the silkworm must 

 be mentioned in any discussion of Entomology. Sericulture has not 

 yet attracted much attention in Africa, but there is no doubt that 

 there is opportunity for a minor industry. In 1929-30, Mr. Norton 

 Breton, Chairman of the Imperial Institute Advisory Committee 

 on Silk Production, visited the Union of South Africa, Rhodesia, 



