64 
NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 
an average of 29.8 red-fungus pustules per leaf, the degree of white- 
fly infestation agreeing quite closely with rows 4 to 1 1 (Table X) of 
the experimental grove. 
(2) Swindley grove, near Orlando, Fla. More than 80 per cent 
citrus white fly; less than 20 per cent cloudy-winged white fly. — In this 
grove of 900 seedling oranges experiments were conducted during 
the summer of 1908 to determine what advantage might follow two 
introductions during the same season, and incidentally, one intro- 
duction on each of two successive years. About one-fourth of the 
trees were sprayed with no fresh red Aschersonia, 1 one-fourth with 
fresh red-fungus mixtures varying to strength (300 to 625 pustules 
per gallon) during July, and another fourth in a like manner during 
July and August. The remaining fourth, which had been sprayed 
during July, 1907, was again sprayed in August, 1908. The results 
are given in Table XL 
Table XI. — Red Aschersonia: Results of experiments in spreading the infection. 
Block 
No. 
Fungous introductions. 
Leaves 
exam- 
ined. 
Pupa 
cases per 
leaf, 
average. 
Red As- 
chersonia 
infection, 
average 
per leaf. 
Unsprayed check 
Sprayed once. July. 1908 
Spraved twice, Julv and August, 1908 
Sprayed twice, July, 1907, and August, 1908 
0.01 
6.1 
7.3 
2.9 
While the data presented show that more fungus developed on the 
trees sprayed twice in one season, the spread of the fungus on all trees 
during the season of 1909 was so rapid that it became impossible to 
tell which trees had been sprayed once, twice, or not at all. All 
developed an equally large amount of fungus which, supplementing 
unexplained mortality, so held the fly in check that the fruit in the 
grove was practically clean by the following fall. By the following 
spring much of the fungus had fallen off and there were more specimens 
of the fly in the grove during 1910 than the owner had noticed for 
many years, and the trees became thoroughly sooted. 
(3) Drennen estate grove, near Orlando, Fla. The citrus and 
cloudy-winged white flies present, the latter comprising 0.8 per cent, 
according to an estimate made in June, 1909. — In this experiment a 
solid block of six rows of eight trees each was divided into two series, 
one comprising the even and one comprising the odd numbered trees 
of the six rows. Only a trace of red fungus (no yeUow or brown) had 
been found in this grove and none had been discovered near the 
experimental block. After the first introduction, therefore, the 
experiment is properly one of increasing the efficacy by spreading 
the infection. An attempt was also made to introduce and spread 
the yellow and brown fungi by including their spores and mycelial 
i This fourth was composed of trees either not sprayed or sprayed with dried pustules of the Ascher- 
gonias later determined to be valueless. 
