210 SCIENCE IN AFRICA 



cial conditions differing widely from the ecological environment 

 in which such trees grow in the wild state. 



Most of the published work on forest entomology comes from 

 South Africa and deals with wood-borers, the eucalyptus snout- 

 beetle, and insects affecting Pinus insignis. The presence of an 

 entomologist occupied entirely with forest problems, on the staff 

 of the division of plant industry in the Union, is of note; his fine 

 work on the eucalyptus snout-beetle, which has led to the control 

 of this pest, is one of the few successful applications of the principle 

 of biological control in Africa (see Chapter X, p. 290). Pinus 

 insignis has proved to be very susceptible to disease in parts of 

 South Africa, though not in the large winter rainfall area of the 

 Western Gape Province, where this tree is very much at home. Its 

 diseases have been studied in the botanical department of the 

 Witwatersrand University. The botanical department at Stellen- 

 bosch University also studies diseases of trees in collaboration with 

 the pathological section of the division of plant industry. 



As a special entomological problem, the gall-fly [Phytolyma lata) 

 of Chlorophora excelsa, an important timber tree of Uganda and 

 West Africa, has for some years been regarded as a serious pest, 

 the investigation of which is by no means yet complete. 



