YOUNG GEOWTH OF CITRUS DESTROYED BY INSECTS. 27 
autumn had shown to occur throughout this region. Efforts soon 
were rewarded with the finding of living parasites in very small 
numbers on the mo r e 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 very 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 lahorensis, being 
a true internal parasite of the white 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 
Aleyrodes citri. Moreover, the journey from India to Florida occupies 
between five and six weeks, while the entire 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 
cj^cle of development would take place and the adults emerge before 
America was reached. This latter feature necessitated the presence 
of living Aleyrodes throughout the journey so that the parasites 
at time of their emergence would have material upon which to work. 
As small 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 all were free from living white flies. Young 
fly-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 from 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, Pliyllocnistis citrella Stainton 
(PL VII, fig. 1) as well as by a bud- worm (Agonopteryx sp.), that the 
young leaves of all the plants curled and shriveled before reaching 
maturity, thus rendering the plants worthless for the purpose desired. 
In order to avoid the destruction of young growth by these two 
insect pests cloth houses were constructed and into these were placed 
