36 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 



produce countless spores. To the casual observer the flies appear 

 merely to die and slirivel up on the leaf as shown in Plate IX, upper 

 figin-e. 



In connection with this fungus the authors' observations have been 

 limited to the vicinity of Orlando, but Prof. Fawcett, to whom crccUt 

 is due for its determination, has seen it several times working in 

 cUfTcrent parts of the State since August, 1908. Wliile it has been 

 reported by Dr. Berger ^ as attacking the larvse of the citrus wliite 

 fly, and has been seen by the authors attacking the eggs of the same 

 species, it must be regarded, so far as now known, as primarily a 

 parasite of the adult. 



Notwithstanding the very large number of adults it is capable of 

 killing when spreading most rapidly during the fall, it can not be said 

 that it has proved itself of any value in checking the progress of fly 

 infestation for the reason that a sufficiently large number of adults 

 escape to deposit as many eggs as the new growth can well support. 

 During September and early October, 1908, when this fungus was 

 spreading very rapidly and there were in places from one to several 

 hundred dead flies per leaf and it appeared that much good was being 

 accomplished, careful examination of the leaves of the new growth 

 showed that they were heavily infested with eggs. In a grove near 

 Turkey Lake, 8 miles west of Orlando, where the Sporotrichum was 

 even more virulent in its attack upon the cloudy-wdnged white fly, the 

 surviving adults so overcrowded the leaves with eggs that on many 

 shoots not a larva was able to mature. These observations have been 

 mentioned to show that, if anything, the killing of an even compara- 

 tively large number of the fall brood of adults may act as a stimulus 

 rather than a check to the progress of infestation, inasmuch as it seeks 

 to prevent that overdeposition of eggs, which, in itself, as explained 

 elsewhere, is. an important element of self-control with tliis speciess 



Thus far the authors have not been successful in attempts at spread- 

 ing the Sporotrichum artificially. During September, 1908, many 

 thousand infected flies were collected for experimental purposes. On 

 October 8, when the fungus was spreading less rapidly than during 

 September, two watershoots were rubbed with infected flies, and 

 although adults of both species fed on the leaves for two weeks none 

 became infected. One hundred adults caged on a leaf smeared with a 

 paste made of 100 infected flies and water did not become infected, 

 neither did adults confined on leaves sprayed with a solution of 100 

 infected flies in one-fourth of a cup of water. Experiments vnih the 

 same material on May 29 and August 17, 1909, gave equally negative 

 results, although adult citri were abundant on the treated leaves. 

 Leaves of china tree and orange were dipped and sprayed with a water 

 solution of infected flies, were rubbed with a paste made of flour and 



» Bui. 97, Fla. Agr. Exp. Sta., p. 56, 1909. 



