CHAPTER VIII 



ENTOMOGENOUS FUNGI 



The occurrence of fungus parasites attacking insects has long 

 been known in certain cases, but in recent years this knowledge 

 has been considerably increased, and, as regards tropical forms, is 

 capable of very much greater extension. The rich insect fauna 

 and moist conditions of Trinidad, for example, yield in suitable 

 situations and on various types of hosts a large variety of forms, 

 most of which appear to be as yet undescribed and are certainly 

 unstudied. The scale insects (Coccidae) of that island, though 

 numerous in species, are relatively unknov^n as pests, a position 

 mainly due, it would appear, to their inability to attain to large 

 numbers without suffering from an epidemic of fungus disease. 



The remaining islands are more or less subject to annual 

 or occasional outbreaks of scale, and the control of these by 

 fungi has been the subject of considerable attention, mainly as 

 a result of what might fairly be called the white-fly fungus boom in 

 Florida a few years ago. 



Our knowledge is yet far from exhaustive, even in the limited 

 field of scale-insect parasitism, either as to the fungi concerned 

 or their relative distribution and efficiency, but certain general 

 principles have by now emerged. 



While these are not different from what might have been 

 intelligently anticipated, they are valuable as being the results 

 of experience and observation. As such they may be worth 

 stating in view of the impossible hopes which still linger here 

 and there with regard to the artificial distribution of these fungi. 



Speaking first of all quite broadly, it may be said that the 

 efficiency of the fungi is proportional to the humidity of the air 

 amongst the plants on which their hosts occur. Their relative 

 abundance in the islands of the Windward and Leeward groups 

 follows pretty closely the amount of rainfall usual to each island, 

 though the distribution of rain is so local that the wetter islands 

 each have areas in which the fungi are of little use, and the driest 

 island has sheltered moist situations in which they are effective. 

 Still speaking broadly, it may be said that in Dominica, in normal 

 years, the control is as efficient as natural agencies can well 

 produce. Conditions are generally such that fungus parasites 

 keep in check established colonies of scale and follow so closely 

 on new infestations that the effects of the insects are negligible. 

 In most parts of St. Lucia, and in the most humid districts of 

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