46 EEPORT OF SEARCH FOR ENEMIES OF CITRUS WHITE FLY. 



westward throughout northwestern and north-central India. He has 

 also seen this insect at Macau, in southern China, while in the collec- 

 tion of this bureau in Washington is material on orange leaves col- 

 lected at Canton, southern China. These records are sufficient to lead 

 to the belief that the white fly occurs on citrus plants throughout 

 southern Asia. If citrus is the original food plant of this insect (but 

 we have no conclusive evidence that it is) it would then appear quite 

 probable that its original home was in that part of southeastern 

 Asia in which citrus plants originated and that it followed the dis- 

 tribution of the citrus through other parts of that continent. 



In India the white fly prefers Jasminum as a host plant over citrus 

 trees. On this plant the insect was of much greater occurrence and 

 capable of withstanding climatic conditions better than on any other 

 host. Viewing the problem entirely from the standpoint as seen by 

 the writer m India, it would appear that Jasminum was the original 

 host rather than citrus. The most commonly cultivated species of 

 Jasminum, called samhac, is considered a native of India, but other 

 allied species are native to China. Various species are cultivated 

 throughout subtropical Asia. Hence it is quite probable that the 

 white fly infests this plant in China as well as in India. 



The lightest infestation of the white fly occurs in the eastern part of 

 India while the most severe infestation is in the northwest. Consider- 

 ing climati'c conditions one would expect the contrary, as the weather 

 of Assam is of greater humidity and less extreme temperature than 

 the upper country. Trees in the Kliasia Hills at between 1,000 and 

 1,500 feet elevation and surrounded b}^ forest trees so as to be abun- 

 dantly protected by shade were so lightly infested that only an occa- 

 sional insect could be found and most of these were parasitized. 

 Although the infestation in the northwest was so light that the insect 

 was in a satisfactory condition of control it could be generally stated 

 to be much more severe than in eastern India. This condition, 

 together with the fact that the only known reports of injury from the 

 white fly received in the Indian Museum came from the northwest 

 during the early nineties, leads the writer to believe that this insect is 

 of recent introduction into that region. 



After all has been said and wc know that citrus and Jasminum 

 are the present preferred food plants of Aleyrodes citri in southern 

 Asia, nobody is able to state definitely that either is the original host, 

 even thougJi indications would tend to point that way. Nevertheless, 

 it is sufficiently certain as to be considered a fact that the citrus white 

 fly is a native of the semitropical part of continental Asia, and the 

 strongest indications pomt toward the Indo-Chinese region as its 

 original home. 



