2 BULLETIN 1117, U. S. DEPARTMENT OF AGRICULTURE. 
ous insects by entomogenous fungi. It is favored by a rainy season, 
more or less well defined, lasting from June to September, which 
correlates reasonably well with the growing season of the trees. The 
more important insect pests in a large measure are dependent upon 
the new growth or "flush" of the citrus trees for their successful 
development and reproduction. Hence the period of maximum 
abundance of these insects, which naturally coincides with the period 
of greatest food supply, at the same time coincides with the rainy 
season. This is fortunate, for the environmental factors which are 
normally present in the summer during periods of greatest insect 
injury are very favorable for the development of the various species 
of fungi that prey upon and destroy the injurious insects. 
These entomogenous fungi are worth millions of dollars to the 
citrus industry. Owing to their excellent work, oranges and grape- 
fruit are grown at a profit in many parts of the State where no 
money whatsoever is spent on artificial remedial measures. It should 
not be inferred that spraying to control citrus pests is not advised. A 
greater profit can be enjoyed when sprays are employed judiciously, 
particularly if they are utilized in a way to supplement the work of 
the fungi, but citrus fruits can be grown at a profit in the absence 
of any artificial measures, a condition probably not possible, for in- 
stance, in the apple industry. The inestimable value of the entomo- 
genous fungi to the citrus grower of Florida is thus evident. 
If it were possible to eliminate these organisms from the State 
and at the same time permit the injurious insects which they attack 
to remain uncontrolled by artificial measures, the growing of oranges 
and grapefruit would be an extremely hazardous occupation in which 
the monetary rewards Avon Id be negligible or absent. Other things 
being equal, it is estimated that in the absence of these fungi the 
annual citrus crop would be reduced by at least 50 per cent, so great 
would be the injury wrought by scale insects and the white fly. 
These statements are based upon the experience of the Federal 
agents, the State specialists, and the growers themselves, who, while 
permitting other factors to function normally, have at times inad- 
vertently or otherwise eliminated in small areas, by sprays of Bor- 
deaux mixture, the entomogenous fungi, which are killed effectively 
and completely by this fungicide. They have found that trees 
sprayed with it afford excellent feeding places for the insect pests, 
and that as the development and reproduction of the latter are unim- 
peded by the entomogenous fungi, they multiply prolifically, caus- 
ing heavy defoliation, a very high percentage of fruit drop, and 
unsightly unmarketable fruit, and even threaten the very life of the 
trees. 
