CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. 9 
the petals have all fallen, and the thrips then seek the young fruit. 
The petals do not all fall at once, but come down gradually, and the 
transfer of thrips is therefore gradual. 
The first application should be made as soon as four-fifths or more 
of the petals have fallen. This checks the imsect at a time when the 
orange is most susceptible of deep injury and when the blossoms have 
passed the period at which pollmation might be mterfered with by the 
spray. 
After the first application more larvee will issue from eggs deposited 
in the very young fruit, and additional adults will appear from the 
specimens pupating at the time of the application. The second 
application must therefore be timed to prevent this renewed attack, 
which may be expected to reach the danger pot in from 10 to 14 
days after the first spraying. ‘This second spraying should not be 
too long delayed, as a comparatively few larve may, by their persist- 
ent habit of feeding in a circle about the base of the fruit, cause con- 
siderable injury. Special effort should be made to drench all the 
fruit as well as the few remaining tender leaves thoroughly, as it is 
here only that the msects occur. 
The third application may be longer delayed if the first two have 
been thorough and. well timed. It generally takes the insects from 
two to three or four weeks to become dangerously numerous again, 
as they reinfest the sprayed trees very much more slowly after the 
second application. 
After the third application the fruit rapidly loses its attractiveness, 
and the insects then find it necessary, in order to secure food, to 
spread out over the few remaining tender orange leaves and certain 
miscellaneous food plants. Durmg the latter part of August and in 
early September there is usually another abundant growth of shoots 
upon which the thrips congregate 1 great numbers. A fourth appli- 
cation in late August or more probably in September should be timed 
to catch the insects as soon as they become numerous and before any 
ereat amount of leaf injury appears. 
The importance of protecting this growth is evident to those 
familiar with the stunted condition of orange trees in certain orchards 
of Tulare County as the result of continuous feeding of large numbers 
of thrips during the first five or six years of growth. The writer has 
in mind an orchard in which trees five years from the nursery are 
no larger than the average 2-year-old trees in localities more favor- 
ably situated with regard to thrips, and which each year have a 
very large percentage of the leaves so severely injured that they roll 
up into tight curls. 
