30 REPORT OF SEARCH FOR ENEMIES OF CITRUS WHITE FLY. 
Europeans require heavy protection in order to withstand it. Then 
frequently hot blasting winds blow with great violence, stirring up 
the dust in dense clouds and rendering life doubly uncomfortable. 
In the direct rays of the sun the temperature during this time 
often exceeds 150° F. Failing rains cause vegetation to dry 
up and insects develop with difficulty. The following instance shows 
the effect of drought on the white fly: 
In the Government Horticultural Garden at Lahore there is a very 
large nursery containing small orange and lemon trees. These trees 
were free of living Aleyrodes with the following exceptions: At 
one side of the nursery there was a large, densely foliated deciduous 
tree which overshadowed a number of orange trees. Some of 
these trees which were more densely shaded contained a small number 
of living white flies. Near the center of the nursery was a densely 
foliated tree about 10 feet tall, against the base of which were two or 
three small orange trees which were in shade throughout the day. 
These trees contained some living white flies, whereas other trees 
immediately surrounding but exposed to the sunshine contained 
none. Moreover, it can be stated that at no place in India did the 
writer find living Aleyrodes on small nursery trees except in situa- 
tions that were well protected by shade. 
The most severe and at the same time extensive infestation of the 
white fly on citrus- in India occurred on a large hedge at Lahore, and 
this was utilized in the writer's breeding and collecting work. A 
part of this hedge was protected by a cloth awning and this protected 
portion was infested on all parts. (See PI. VIII.) On the part not 
covered with awning the white fly occurred in abundance only where 
the hedge was protected by densely foliated overhanging trees which 
kept the direct rays of sunlight from the hedge plants throughout 
the heat of the day. The side of the unprotected hedge exposed to 
the direct rays of the afternoon sun was entirely free of living white 
flies, whereas on the lower part of the opposite side, which was in 
shade except for a very short period in early morning, living flies 
could be found in considerable numbers. 
In the case of large citrus trees the greatest number of living 
insects was invariably found in those having the densest foliage. A 
tree in which the foliage was light seldom contained living flies 
except where protected by the shade of a large overhanging species. 
Although the white flies appeared to prefer trees of the tangerine 
variety, they were seldom able to multiply to any extent on these 
because of the small leaves and the less dense foliage than that of 
other varieties. In any species of citrus in which living specimens of 
the white fly occurred the infestation was found almost invariably in the 
shadiest part of the tree or the interior part near the main branches. 
