18 BULLETIN 1225, U. S. DEPARTMENT OF AGRICULTURE. 
SEASONAL HISTORY. 
In the warmer parts of Florida the camphor thrips is active and 
reproduces at all times of the year, but in the more northern parts 
of the State, especially at Satsuma and Waller, where the largest 
number of camphor trees are growing, it is doubtful if they reproduce 
through the winter. Professor Watson states that breeding ceases 
at Gainesville during the winter. Adults are known to hibernate 
there, and it is difficult to find young larvre during the colder months. 
Such is not the case at Orlando, however. The breeding experiments 
recorded in this bulletin were conducted through the winter at the 
laboratory in Orlando but under natural climatic conditions. Checks 
and daily observations made on trees growing in the laboratory yard 
have confirmed the results as given, and show that the thrips exist 
in all stages throughout the year. 
During the late fall and winter months the thrips were especially 
abundant on the trees at Orlando, perhaps more so than at any 
other time of the year. On April 1 fewer thrips were noted, and 
they continued to decrease in numbers for about two months. The 
same condition existed at the camphor plantation at Satsuma. 
During April and May very few- thrips were in evidence, and the 
camphor growers reported that they were never injurious at that 
time of year. During June they began to appear in considerable 
numbers and caused injury to .the trees, being found mostly on the 
young buds, many of which were blackened and killed. The thrips 
continued to work on the trees throughout the summer, feeding on 
the bark when there are no buds or new growth. At Satsuma their ac- 
tivity ceases about November and little breeding takes place until 
March, unless spells of warm weather occur during the winter. At 
Orlando, however, they continued to live and increase on the camphor 
trees throughout the winter 
It was always observed that no thrips were in evidence on the 
trees on a cold morning. When the temperature was down to 
50° F. they remained down in the bark lesions on the older limbs. 
It was not until the sun had warmed up the atmosphere that they 
would come out on the bark and leaves to feed. By cutting open 
the lesions the insects could be found in all stages. They feed there 
on the bark and cambium tissues and often remain for several davs 
at a time if weather conditions are unfavorable. In fact it is in 
these lesions that the adults hibernate through the entire winter in 
the northern part of the State. Cloudy or rainy weather even in 
summer has a tendency to drive the thrips to the shelter of the 
bark lesions. They show a decided positive reaction to sunlight and 
are found in the tops of the trees on bright days only. 
HOST PLANTS. 
As far as is known, the camphor thrips will live only on the camphor 
tree, Cinnamomum camphora (L.) Nees & Eberm. Experiments 
were conducted to determine if it would live on other closely related 
trees, including bays (Persea spp.), avocado, Persea americana Mill., 
and sassafras, Sassafras variifolium (Salisb.) Kuntze. These are 
included with the camphors in the family Lauraceae and are native 
in the parts of Florida where the camphors grow. It was thought 
