12 
BULLETIN 885, U. S. DEPARTMENT OF AGRICULTURE. 
groves were available for observation either in the Canal Zone or 
near-by portions of the Republic of Panama. 
Infestations started by adults carried on vehicles or on the cloth- 
ing of men working among infested trees and then going to unin- 
fested ones have not been seen. However, the first-mentioned, 
writer, after making observations on trees on which adults were ' 
common, has carried stray individuals on his clothing at least 
3,000 feet. 
The rate of spread or infestation on infested trees has been deter- 
mined in the following ways : First, taking a shoot that is beginning 
to grow and watching the number of new spirals laid on the leaves 
of said shoot; second, taking shoots at the beginning of the rainy 
season and checking the number of egg spirals laid on the leaves 
of said shoots. In this latter method shoots of the preceding season 
were selected and the rate of infestation on this mature growth as 
well as on new growth that started from the tip of the mature ^ 
growth was determined by the number of eggs laid on such growth. 
The first method is illustrated by the record kept on a young 
shoot of orange from October 23 to November 17, 1918, or from the 
time that this shoot had grown from 3.5 to 11 inches long. No 
eggs were laid before November 5 and the leaves are numbered 
from the bottom of the growth upward. 
Table I. — -Number of egg spirals laid by the black fly on young orange shoot. 
Leaf 
No. 
First 
spirals 
laid. 
Num- 
ber. 
New spirals laid on November — 
To- 
tal. 
6 
7 j 8 9 
10 
11 
12 1 13 14 
1 
15 
16 
17 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
Nov. 5 
Nov. 6 
Nov. 8 
...do.... 
Nov. 9 
Nov. 12 
Nov. 13 
...do.... 
Nov. 14 
Nov. 13 
2 i 3 
1 
3 








1 

3 
2 






2 
1 
10 
5 
4 





2 
1 

1 
o 



o 

2 
3 

2 
2 





2 
1 


3 
3 




2 
2 
2 
1 
1 
4 
2 
1 

1 
17 
17 
19 
11 
14 
7 
2 
1 
1 
1 

1 
1 
3 
3 
2 
4 
3 
2 
1 
1 
1 
3 








2 
2 
1 
2 
4 
1 
Nov. 14 
Nov. 15 
1 
1 






s 
o 







1 

1 
No eggs were laid on this shoot between November 15 and Decem- 
ber 1; observations, therefore, were discontinued. In this case it 
must be borne in mind that the old growth of this tree was heavily 
infested with A. woglumi in all stages of development, and that the -E 
adults were abundant on the young growth up until November 17, 
after which a decided dropping off took place, so that during the 
period from November 23 to December 23 very few adults were 
present on the entire tree. On April 8, which is just at the end of the 
dry season, the eggs on a 19-inch long shoot were counted and found 
