8o DISEASES OF CROP PLANTS 



Sporotrichum globuliferum, and a temporary high death-rate 

 has been produced by spraying the spores of this easily cul- 

 tivated fungus on thrips-infested trees in Grenada. 



Of the plant-feeding bugs, Dysdercus spp. the cotton stainers 

 and Nezara viridula, the green bug, have been seen to be subject 

 to epidemics of Sporotrichum globuliferum and Isaria Pattersonii, 

 respectively. 



The froghopper in Trinidad is attacked every year by 

 Metarrhizium anisoplics and an Empusa sp., which destroy 

 large numbers of adults when conditions are favourable. 



An epidemic outbreak of disease caused by Botrytis rileyi, 

 on caterpillars [Thermesia gemmatalis ?) infesting a field of cow- 

 peas in St. Kitts, was so sudden in its effects that the stiffened 

 bodies clinging to the leaves produced the appearance of a 

 sprinkling of snow. 



The sugar-cane moth borer Diatroea is subject in the larval 

 stage to the attacks of Isaria Barbcri. 



Gibellula arachnophila is fairly common on leaf-inhabiting 

 spiders. 



Besides these established examples there are many indi- 

 vidual records of species of which the distribution is unknown. 

 There can be no doubt that fungus parasites play a considerable 

 part in controlling the numbers and distribution of insects, a 

 control which in many cases is the less conspicuous because of its 

 efficiency. Its importance in regard to scale insects is strikingly 

 demonstrated by the infestations which develop on citrus trees 

 after spraying with Bordeaux mixture, which suppresses the 

 fungi without affecting the insects. 



