THE CAMPHOR THPJPS. 3 
between the nodes, the cut end invariably died back to the node. 
In these dead ends injurious fungi and borers developed and often 
then effect extended beyond the node. 
Plants thus treated are always stimulated to new growth. When 
this occurred in late fall or winter the trees were not able to resist low 
temperatures which an unpruned tree could withstand without the 
slightest damage. The combined effect of the method of pruning 
and the injury from cold was a great set-back to the growth of the 
trees, resulting in the dying back of many large limbs and in some 
cases the death of the trees. 
The camphor thrips was a third obstacle to camphor production. 
This pest appeared in great numbers on the cut ends and on the new 
shoots that follow pruning. This new growth appeared to furnish 
an unlimited food supply for the thrips. which multiplied without 
any apparent restriction. The effects of the thrips on trees thus 
pruned was very marked. Plate IV, B. shows a tree attacked by the 
thrips. following the usual pruning, resulting in the death of many 
of the limbs. 
To discover means of controlling this pest, preliminary investiga- 
tional work was carried on by Prof. J. R. Watson (3, 6'), 3 Florida 
Agricultural Experiment Station, Gainesville, Fla. This work 
showed that the insect was spread over the entire plantation at 
Satsuma, Fla., and also indicated that it would be a difficult and 
expensive pest to control by any artificial means. The seriousness 
of the situation led Congress to appropriate funds with which to 
work out some economical method for the commercial control of this 
pest. The work began as a special project of the Bureau of Ento- 
mology, with Professor Watson cooperating. After about a year the 
project was placed under the Tropical and Subtropical Fruit Insect 
Investigations, where it was continued over a period of two more 
years. 
HISTORY AND DISTRIBUTION. 
The camphor thrips was first discovered at Satsuma, Fla., in 
November, 1912, by William O. Richtman (8), who found the pest 
spread over the entire plantation and was very much alarmed by its 
apparent ravages. It has since been found in many parts of Florida, 
including Orlando, Clearwater, Oneco, Sebring, Daytona, Fort Pierce, 
and Glen St. Mary, and no doubt may be found in all locations about 
these places. In fact its range is now known to cover all of Florida 
except the extreme southern part. Search has been made for it in 
Dade County but without success, though very few camphor trees 
are grown in that part of the State. The thrips also occurs on camphor 
trees in Alabama, Mississippi, and Louisiana, and probably in Georgia, 
since it has been found close to the Florida-Georgia State line. In 
all probability the camphor thrips will be found throughout the range 
of the camphor trees. Camphor trees grown as ornamentals will 
probably not suffer to any serious extent from the ravages of this 
pest, but it is quite certain that in hedges which are pruned back 
at frequent intervals camphor will be severely damaged by the 
thrips, a fact which may necessitate the abandonment of camphor 
for ornamental hedges. 
3 Figures in parenthesis (italics) refer to "Literature cited," p. 29. 
