40 REPORT OF SEARCH FOR ENEMIES OF CITRUS WHITE FLY. 
down the natural enemies of this pest as well. Probably the adults of 
Prospaltella never emerge from the majority of parasitized larvss and 
pupse of the fly, and this because of their destruction by heat previous 
to the time for their exit. This same extreme weather which limits 
the white fly to two distinct broods has both a direct and an indi- 
rect effect on the lady-beetle. Since this insect destroys only the 
younger stages of the white fly, the heat has an indirect effect by 
limiting the breeding of the pest to two distinct broods, so that there 
is only a very short time in the spring and in the fall during which 
food for the coccineilid is available. The direct effect is that the ex- 
treme heat produces a deterrent influence on the lady-beetle's activity. 
It may be well to state what could be expected of these natural 
enemies if established in Florida. At the very maximum of possible 
efficiency the writer believes they would fall far short of commer- 
cially controlling the white fly. In fact, it is very doubtful if its 
commercial control by natural enemies alone is possible. Granting 
that this high degree of control could not be expected, the writer's 
observations and experience lead him to believe that the introduction 
of these natural enemies,- especially the lady-beetle, is likely to result 
in sufficiently beneficial results to be well worth the while. Espe- 
cially would this be so when these natural enemies were working in 
connection with the different fungous enemies of the fly now found 
in Florida. 
The elimination in this country of the checks to the development 
of these natural enemies, which exist in India, would assuredly have a 
beneficial effect. Whereas in India the white fly can be found on 
citrus trees only in small quantities and is limited to two distinct 
broods, the situation is entirely changed in Florida in that there are 
several broods in a single year. The presence of an adequate food 
supply throughout a large part of the year, in a climate in which the 
most extreme day of summer is sufficiently mild to allow their free 
activity, would seem to present such a favorable situation that these 
natural enemies of the white fly must needs accomplish excellent 
results after becoming thoroughly established. 
DESIRABILITY OF CONTINUING THE ATTEMPT TO INTRODUCE 
THESE TWO NATURAL ENEMIES. 
It has been pointed out in the preceding discussion that conditions 
in Florida appear favorable to splendid results from the establish- 
ment of these natural enemies, especially the lady-beetle (Cryp- 
tognaiha Jiavescens) . As previous experience has shown how best to 
cope with the situation in order to carry it through to a successful 
termination, the present would seem an inopportune time to termi- 
nate endeavors in parasite introduction. We have detailed informa- 
tion of localities in which to find the natural enemies, the proper 
