72 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 
so reliable as the spore-spraying method for the Aschersonias. The 
infections secured by artificial means of introducing fungi, while 
successful in introducing the fungi, have thus far proved of little 
or no avail in increasing their efficacy after they have once be- 
come generally established in a grove. Experiments by the 
authors, and by citrus growers in cooperation with the authors, 
involving the treatment of thousands of trees with suitable "checks" 
or "controls" have shown that when fungus (red or yellow Ascher- 
sonia) even in small quantities is present in a grove there is no cer- 
tainty that from three to six applications of fungous spores in water 
solution will result in an increased abundance of the infection on the 
treated blocks of trees by the end of the season. In some of the 
most important and carefully planned and executed experiments 
the fungus has increased more rapidly in sections of the groves which 
were not sprayed with spore solutions than in the experimental 
blocks. In no case has practical benefit been observed to result 
from efforts to increase the efficacy of the fungi in groves where 
they previously occurred. The above remarks apply especially to 
the Aschersonias. With the brown fungus, efforts to increase the 
efficacy have been equally disappointing from a practical standpoint. 
As a result of the investigations reported herein and of observa- 
tions and experience covering a period of four years the authors 
conclude that there are at present no elements of natural control 
herein dealt with which can be relied upon to give satisfactory re- 
sults. Under present conditions it is unquestionably more profit- 
able to depend upon artificial remedies. 1 
There are, however, certain circumstances under which fungous 
parasites may be used to advantage. First may be mentioned the 
comparatively few citrus groves located in hammocks, with trees 
growing without regularity and with conditions such that fumiga- 
tion or spraying with insecticides would be impracticable. 2 Second 
are those groves which are so situated that the failure to more 
than partially control the white flies will not interfere with the con- 
trol of the insects in other groves and which for any reason it is 
impracticable to place on the most profitable basis of productiveness. 
While it is recognized that everything possible should be done to 
secure and to test every procurable and possible enemy of both the 
citrus white fly and the cloudy-winged white fly, citrus growers in 
Florida should not await the outcome of this work with in activity 
1 See Bui. 76 and Circular 111, Bur. Ent., XT. S. Dept. Agr. Fumigation has already been dealt with 
in publications of the bureau. • Spraying and other matters connected with artificial methods of control 
will be treated in later publications. 
2 Since the above was written the brown fungus has been so effective in controlling the white fly in 
certain very low-lying hammock groves in Lee County that it must be conceded this fungus has made 
artificial remedial measures unnecessary. Such groves, however, are an exception to the rule at the 
present time. 
