NATURAL EFFICACY OP FUNGOUS PARASITES. 



43 



Table IX.- 



-Slal us of ii'Jiite flies and their fungous parasites iit < Ifjlit r/rooes, December, 

 1908, to December, 1909. 



I See Table TI. 



As refi;ar(ls blackenins; of the fruit and foliai;::e, which is the most 

 important element of injury by the white flies, groves 1, 3, 4, and 5 

 were not l^enefited by the work of the parasitic fungi during either 

 1008 or 1909. By the 1st of July, 1909, these groves were at least 

 as black as the average infested grove in which no fungous parasites 

 were established. ISforeover, there were sufTicient live insects present 

 to continue this condition regardless of any unusual climatic condi- 

 tions which might favor the multiplication of the fungous diseases. 

 As regards the reduction of the insects themselves, the fungous diseases 

 were decidedly effective in grove No. 1, promising a condition of 

 freedom from white-fly injury in 1909, The condition of groves Nos. 

 3 and 5 did not give promise of such condition, since any number of 

 live white flies (pupaO above 10 per leaf in December is strong indi- 

 cation that the insects wall multiply sufficiently the following spring 

 to cause a decidedly injurious blackening of the foliage and fruit 

 before climatic conditions will give the fungous parasites an oj)])ortu- 

 nity to check them. Without interference by adults migrating from 

 other groves, an average of 12 overwintering insects per leaf has been 

 noted to produce a general blackening (moderate) of new spring 

 growth of foliage by June 15, while an average of 2.6 live insects per 

 leaf in December was noted to result in a very heavy infestation one 

 year later with excessive blackening of the foliage. As is often the 

 case, in this latter instance the foliage appeared entirely clean up to 

 midsummer, most of the blackening appearing in September and 

 October. 



On the July examination of No. 4 it was found tluit the average 

 number of forms ])er leaf representing the insects which jiroduced 

 the condition noted consisted of 26 dead larva) and pupa^, 8.8 live 

 larva) and pupa?, and 1.9 pupa cases. No. 8 was in a satisfactory 



