124 ENTOMOLOGICAL SOCIETY 



Florida are quite different from those obtaining in California 

 for the common scale insects of citrus trees in that State. In 

 Florida the white fly occurs in the winged state substantially 

 during ten months of the year. There are no winged insects 

 from the latter part of December till toward the end of Feb- 

 ruary. Fumigation is only practicable during this brief period, 

 because otherwise the flying insects would many of them escape 

 and quickly reinfest the trees. Thoroughgoing experiments 

 are under way this winter in fumigation as a continuation of 

 those begun the season previous, and the process has been very 

 fully worked out for the Florida conditions and the particular 

 problem of the white fly. 



No parasites of the white fly have been discovered, nor has 

 it been possible up to the present time to introduce from other 

 regions parasites of other species of white fly. Efforts to 

 accomplish such introductions are, however, in progress. 



The most important natural means of control of this pest are 

 the fungous diseases which attack it, viz., the red, yellow, and 

 brown fungi. A fourth fungus, known as the white fringe 

 fungus {Microccra sp.) has recently been described by Prof. 

 P. H. Rolfs. These fungi, notably the red, brown, and white 

 fringe species, originated in the Manatee region, and have 

 spread from this region now pretty well over the State, follow- 

 ing the spread years ago from the same region of the white 

 fly. In Manatee County, where the fungi are fully estab- 

 lished, they are able practically to exterminate the white fly 

 once in three years, so that every third year the fruit is clean 

 and requires no washing. The following year the insect again 

 flourishes because the white fly fungi have disappeared, having 

 during the clean year nothing on which to develop. Toward 

 the end of this year, however, the fungi again begin to operate, 

 but not sufficiently to prevent the complete blackening of the 

 foliage and fruit during the following or third year. Never- 

 theless, during this year the fly is again reduced to practical 

 extinction, so that the year following is a year of clean foliage 

 and fruit. Means of disseminating these fungi artificially 

 have been extensively experimented with, and it seems possible 

 that their beneficial action can be considerably increased by 

 artificial means. Doctor Morrill has found that some of these 

 beneficial fungi are themselves attacked and destroyed by sec- 

 ondary fungi, but it is not plain that these secondary fungi 

 materially affect the efficiency of the primaries, as the former 

 are more apt to develop after the primary fungus has pretty 

 well exterminated the white fly for the time being. Still, they 

 may at certain times have an important influence on the effect- 



