POSSIBLE EFFICIENCY OF ENEMIES IN FLOKIDA. 39 



conditions in India and from the fact, as he had there determined, 

 that both the parasitic and predaceous enemies of the white fly pass 

 through considerable periods of hibernation, both in the winter season 

 and m the dry season, it seemed to him that the best chance of success 

 was to allow the imported material to go through the winter in a nor- 

 mal condition of hibernation. The alternative was artificially to 

 force, throughout the winter, active breeding of these imported 

 insects and of the white flies as hosts. 



With the exception of a small number of the more active specimens 

 of the lady-beetle enemy of the white fly, an attempt was made to 

 carry the imported msects through the winter m a state of hiberna- 

 tion, with the unfortunate result that none of the parasites or of the 

 lady-beetle enemy of the white fly survived. 



The small number of more active ladybird beetles referred to were 

 removed from the Wardian cases in which they had been imported 

 and taken into the laboratory and placed on young trees infested with 

 white flies in the dormant, pupal stage. The white fly m this stage 

 was not well suited to them as food, which is by preference the egg 

 and early larval stages, and by the 1st of January all but two of the 

 beetles taken into the laboratory had perished. About the middle 

 of January eggs were obtained from white flies reared in the warm 

 room and the two remaining beetles were removed to a small potted 

 seedlmg orange tree stocked with such eggs. The feeding of these 

 beetles on the eggs was voracious and they remained aUve through 

 the winter but as they were apparently of the same sex they died 

 without reproducing. 



The loss of the parasites and the ladybird enemies of the white fly 

 is very regrettable. Possibly such loss can be avoided, if another 

 importation is made at the same period, by adopting the method of 

 keeping the insect enemies and host insects in active breeding through- 

 out the winter in a suitably constructed and weU-stocked greenhouse. 

 Possibly an even better chance of success will come from importations 

 so timed as to arrive in early summer. 



THE POSSIBLE EFFICIENCY OF THESE NATURAL ENEMIES IF 

 ESTABLISHED IN FLORIDA. 



Considering the comparative weather conditions of Florida and the 

 parts of India infested with the white fly, the writer sees no reason 

 why Prospaltella lahorensis and Cryptognatha jlavescens could not be 

 successfully established in this country. 



It has already been stated that neither of the two natm'al enemies 

 of the white fly exerts any great eft'ect in controlling the white ^j in 

 India. The great natural enemy of the white fly in that country is 

 the excessive heat, and this very element which limits the mjuriousness 

 of the white fly is, in the writer's opinion, largely the one that keeps 



