THE CAMPHOR THRIPS. 
19 
that the camphor thrips might have been a native insect living on 
some of these trees, and had taken to the camphor because of their 
close botanical relationship. No evidence to support this theory has 
been found, however. 
BAYS. 
Efforts were made to rear the camphor thrips on twigs of bay 
trees cut and brought into the laboratory, using the same type of 
cage as previously described for the life-history work on camphor 
twigs (fig. 6) . The results of this work are given in Table 4, which 
shows the length of time each lived. Three species of bays were used, 
the swamp bay, Persea palustris, the red bay, P. borbonia, and the 
shore bay, P. littoralis. Observations were made on the scrub bay, 
P. humilis, in its natural habitat, but trees of. this species were not 
available near the laboratory where they could be used for experi- 
mental feeding. 
Table 4. — Length of life of camphor thrips when fed on bay-tree twigs {1920-11 I. 
[a=adult; l=larva; p=pupa.] 
Date. 
Number 
placed 
on bay. 
Died. 
Dec. 14 
5a,51 
5a,51 
4a,41 
4a,41 
4a,41 
3a 
4a 
2a 
81 
Dec. 27, la, 41; Dec. 30, lp; Jan. 3, la; Jan. 6, la; Jan. 8, la; Jan. 10, la. 
Dec. 20, 2 1; Dec. 22, 3 1; Dec. 24, 2 a; Dec. 27, 1 a; Dec. 29, 1 a; Dec. 30, 1 a; 
Dec. 14 
Dec. 30 
Jan. 4, 4 1; Jan. 11,3 a; Jan. 18, 1 a. 
Jan. 18 
Jan. 22, 4 1, 1 a; Feb. 2, 1 a; Feb. 8, 1 a; Feb. 10, 1 a. 
Jan. 18.. .. 
Feb. 8, 3 a, 4 1; Feb. 10, 1 a. 
June 13, 1 a; June 16, 2 a. 
June 22 
June 27, 4 a. 
July 5 
July 9, la; July 11, 1 a. 
July 9, 3 1; July 11, 1 a, 3 1; July 12, 1 1. 
Aug. 11, 4 1; Aug. 15, 1 a. 
Aug. 7, 1 a; Aug. 11, 3 a. 
July 5. . 
51 
4a 
91 
Aug. 23 
Aug. 24, 4 1; Aug. 26, 5 1. 
The data in Table 4 show that camphor thrips larvae can not live on 
bay-tree cuttings. In a few cases they became adult, but most of the 
larvae died after a few days. The adults lived longer, one of them 
reaching 23 days. In nearly all of the cages the adults laid some eggs, 
but more of them were on the cotton stoppers than on the bay-tree 
twigs. In only a very few cases did any eggs hatch, and the young 
larvae could not then be found. They evidently died from lack of 
proper food. 
Thrips were also placed in cages tied over limbs of a growing bay 
tree. On March 15, 1921, 5 cages containing 20 thrips each, in all 
stages, were tied on limbs of Persea palustris. On opening the cages, 
April 6, some adults were found in one cage only. No eggs or larvae 
were present. June 4 the cages contained no thrips in any stages. 
They evidently failed to reproduce on the bay tree. 
A similar experiment was performed later on the same tree. Three 
small wire cages were tied on limbs of the tree on August 12, and a 
dozen thrips liberated in each. After 6 days they were opened and no 
live thrips or eggs could be found in any cage. 
On May 6 several cages containing a dozen thrips each were tied on 
limbs of the shore bay, P. littoralis, at Daytona Beach. After 7 days 
one cage was found to have a few live adults, but on May 28 no thrips 
or eggs could be found in any cage. 
