24 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 



spores are not only spread about by rain but that many are washed to 

 the ground. 



It is probable that dews, and especially the heavy dews of fall, are 

 of greatest value in moistening the pustules, thus aiding in the dis- 

 solving out of the spores from their mucilaginous matrix, so that they 

 may be more readily transported by other agencies. After heavy 

 dews the matrix containing the spores is so soft that portions of it 

 will adhere to any body brought into contact with it, and not infre- 

 quently such a quantity of spores is dissolved out of the pycnidia that 

 they spread out over the leaf for one-fourth of an inch from the 

 pustule, as shown by the reddish coloring matter of the matrix. 

 Because of the adhesive nature of the matrix thus moistened, it is 

 possible, and even probable, that insects play a part in spore 

 dissemination ; yet the failure of this fungus to increase to any extent 

 during an unusually dry period in midsummer or after the summer 

 rains cease, even though the insects remain abundant, is regarded 

 by the authors as significant and leads them to conclude that insects, 

 in general, play a minor role in spore dissemination. 



Microscopic examination of washes from the bodies of adult white 

 flies collected on trees bearing much fungus has not disclosed the 

 presence of the spores. Of still greater importance as direct evidence 

 is the frequently repeated observation that leaves upon which adult 

 flies collected from similar places have been caged, and which have 

 been protected from rain drippings, have seldom developed fungus 

 pustules. In this connection it is also worthy of note that water- 

 shoots, even though more heavily crowded with adults than outside 

 new growth, develop only a slight amount of fungus as compared with 

 the outside growth if not so located as to be easily drenched with 

 rains. It has been generally observed by growers as well as by the 

 authors that rapid dissemination of spores is concurrent with summer 

 rains, and if these fail to fall the fungi are not spread rapidly, no 

 matter how abundant the adults may have been. 



SPECIES OF WHITE FLIES ATTACKED. 



Wliile the red Aschersonia is most effective in its attack upon the 

 citrus white fly and is of economic importance largely in connection 

 with this species, it is frequently found growing upon several other 

 species of white flies. On numerous occasions it has been observed 

 at Orlando and other points in Orange County attacking the cloudy- 

 winged white fly, upon which it develops into unusually large pustules. 

 Thus far, however, attempts at introduction into groves infested 

 only with the cloudy-winged white fly have met with failure from an 

 economic standpoint, although in each instance an infection was se- 

 cured. During the summer and fall of 1907 such a luxuriant growth 

 of fungus upon Aleyrodes inconspicua Quaintance was discovered at 



