YOUNG GEOWTH OF CITEUS DESTEOYED BY INSECTS. 27 



autuniii had shown to occur throughout this region. Efforts soon 

 were rewarded mth the finding of livmg parasites in very small 

 numbers on the more protected parts of the infested hedge. 



Considerations in Collecting and Transporting Prospaltella 



lahorensis. 



As explained under the discussion of the citrus white fly, this 

 insect veiy shortly after hatching from the egg settles down on the 

 underside of the leaf to remain in a stationary position throughout 

 its life. If the leaf is removed from the tree, the insect dies when 

 nourishment is no longer available. Prospaltella laTiorensis , being 

 a true internal parasite of the w^hite fly, is dependent on the living 

 condition of its host in order to attain maturity. From a consider- 

 ation of this situation it was at once evident that the only practicable 

 way of transporting the parasite to America in a living condition 

 was by means of healthy nursery trees infested with parasitized 

 Aleyfodes citri. Moreover, the journey from India to Florida occupies 

 between five and six weeks, while the entke life cycle of the parasite 

 at high temperatures is of about three weeks' duration. This would 

 mean that even if the parasite left India in the egg stage a complete 

 C3"cie of development would take place and the adults emerge before 

 America was reached. This latter feature necessitated the presence 

 of living iVleyrodes throughout the journe}^ so that the parasites 

 at time of their emergence would have material upon which to work. 



As smaU nursery trees are alone practicable for transportation 

 over great distances, it was at once evident that the success of the 

 mission depended on obtaining young trees well infested with the 

 white fly. Young orange trees were available in sufficient quantities 

 at the Lahore garden, but aU were free from living white flies. Young 

 flj^-infested trees had not been seen anywhere in that country. The 

 problem thus resolved itself into the artificial infestation of the trees. 



Destruction of Young Growth of Citrus Trees by Insect Pests. 



A large number of young orange trees fi"om 1 to 4 feet tall were 

 dug and placed in earthenware pots. As these trees contained 

 no young growth, they were placed in a shady place and kept very 

 moist. It is well known that the adult white fly prefers tender 

 growth for oviposition. Young shoots soon developed, but no sooner 

 did the leaves begin to expand than they were immediately attacked 

 so severely by a lepidopterous leaf-miner, PJiyllocnistis citrella Stainton 

 (PI. VII, fig. 1) as well as by a bud- worm (Agonopteryx sp.), that the 

 young leaves of aU the plants curled and shriveled before reaching 

 maturity, thus rendermg the plants worthless for the purpose desired. 



In order to avoid the destniction of young growth by these two 

 insect pests cloth houses were constructed and into these were placed 



