FOOD PLANTS OF CITEUS WHITE FLY. 41 



season of the year for their collection, the most successful methods to 

 be employed, manner of shipment, and all other factors regulating the 

 l^rocedure. A greenhouse could bo prepared in Florida, so that there 

 would be breeding Aleyrodes on hand at all times of the year. 



As an outline of a second attempt at introducing the natural ene- 

 mies of the white fly, the writer would make the following suggestions 

 on the basis of his past experience : The work should be carried along 

 on a more extensive scale than previously and with the object of 

 continuity should the first attempt fail. Two men should be sent 

 abroad, to arrive in India by March 1. This would give time for 

 adequate preparations before the appearance of the first brood of the 

 white fly ui April. Several cases such as were used by the writer in 

 his expedition should be filled with aleyrodid-mf ested trees and trans- 

 ported to India. This would msure a supply of Aleyrodes as well as 

 citms trees should any difficulty be experienced in an attempt to 

 secure either on arrival in India. Having collected a supply of nat- 

 ural enemies, one of the two men could return with the same to America 

 while the second man remamed in India carrying out preparations for 

 securing material from the second brood of the white fly. Then, if the 

 first shipment should prove a failure, no time would be lost in the 

 second attempt. Should the first shipment come through success- 

 fully, as soon as this was definitely known the agent in India could be 

 informed. He could then proceed to the great citrus-fruit-growing 

 regions of southern China and endeavor to find other natural enemies 

 of the white fly in this little-known region, in which it is quite possible 

 the Aleyrodes originated. The writer is very strongly of the opinion 

 that in China there should be other natural enemies not found in India. 



FOOD PLANTS OF THE CITRUS WHITE FLY. 



The citrus white fly has attained its great economic importance in 

 the United States because of its injurious action to citrus fruit trees. 

 Specific consideration of this matter has been given on pages 11-12 of 

 this bulletin. It has been stated by Drs, Morrill and Back that in the 

 Gulf States oranges of the tangerine group are preferred hosts over 

 other varieties of citrus. This same preference was observed by the 

 writer in India. Similarly, other varieties of oranges are preferred 

 to grapefruit, which was always found highly infested or else free of 

 this insect. Lemons and limes appeared to stand intermediate in 

 point of infestation between oranges and grapefruit. Some varieties 

 of limes were quite as mucn preferred hosts as oranges. Although 

 living specimens of the white fly were usually found on the larger 

 leaves of infested plants, because of the greater protection from the 

 sun, it is a point of much interest that grapefruit trees were much 

 less severely infested than the orange, although in general their larger 

 leaves produced a more dense shade than those of the former. 



