CONDITIONS LEADING TO DEMAND FOE SEARCH. 13 
this insect already prevalent in certain parts of Florida. As to the 
comparative efficiency of these three methods authorities are not 
universally agreed, but from an unbiased point of view it would 
seem that each has its advantages over the others within certain 
more or less restricted fields. A discussion of these restrictions is 
unnecessary in this place. Suffice it to say that by 1909-10 results 
of investigations had not established universally in the minds of 
Florida orange orchardists the absolute commercial efficacy of 
mechanical-control methods. 1 
CONDITIONS LEADING TO THE DEMAND FOR A SEARCH FOR 
NATURAL ENEMIES OF THE CITRUS WHITE FLY. 
The climate of Florida is, in general, very damp, a condition 
especially suitable to the free development of fungous diseases. 
Six different fungi have been recorded as attacking the citrus white fly, 
and their resultant destruction in localities of much humidity appears 
at times to total a high percentage. 
Following a movement toward efficient organization of the citrus 
industries of Florida, the extent of damage which results from white- 
fly infestation, as well as its direct bearing on the market quality of 
the fruit, was brought forward with renewed force. Considering 
the failure at that time of the mechanical methods to meet ade- 
quately the demands of the orchardists, coupled with the apparent 
partial efficiency of fungous diseases, the time seemed ripe that the 
popular idea of control by natural enemies should gain a devoted 
following. 
This theory of control by natural enemies, in brief, is that all life 
in its native home is kept in check by other forms of life which prey 
upon it ; in other words, that all nature is in a state of equilibrium. 
Chief among these natural factors of control in the case of insect 
pests are other forms of insect life which are parasitic and preda- 
tory on the noxious form. In recent years much attention has 
been devoted to the discovery and subsequent introduction from 
one country into another of beneficial insects for utilization in 
attempted control of certain of our more important insect pests. 
One of the earliest importations into America was that of a small 
lady-beetle, Novius cardinalis Muls. For several years a large scale 
insect called the cottony cushion scale (leery a purcTiasi Mask.) had 
been producing such extreme injury to the orange and lemon groves 
of California that the industry was threatened with ruin. Mechani- 
cal means of control proved ineffective. In the belief that the insect 
had been introduced into the United States from Australia, Mr. 
i Fumigation, though highly efficient in itself as a factor in the control of the citrus white fly, has 
not met with genera] adoption, largely because of certain practical considerations which render it 
unavailable economically under present conditions in Florida. However, recent results with special 
oil sprays have placed the control of the white fly on a very satisfactory commercial basis. 
