April, '13] HASEMAN: APPLE LEAF-HOPPER 241 



portions of the nursery in which the work is being carried on were 

 planted in breeding cages here at the Experiment Station and in no 

 case were we able to rear leaf- hoppers from these trees. As a further 

 evidence that in Missouri the pest is not carried over in the egg condi- 

 tion, one block which came under the writer's observation consisted 

 of forty or fifty acres of one-year-old apples which had been severely 

 injured two years ago by this pest. The winter of 1911 and 1912 

 was so severe that these trees were cut back to the ground before 

 spring opened with a view of securing strong, healthy one-year-old 

 trees on two-year roots. In the early spring of 1912 the writer ex- 

 amined this block when the pest first became noticeable throughout 

 the nursery and while this block was several miles from apple orchards 

 and in fact no fruit trees at all were within a mile of the ground, 

 still it was found that these young trees, before they became half 

 a foot tall were badly infested with very young nymphs and mature 

 leaf^hoppers. The block under consideration was surrounded in part 

 by woods and creek bottom land where an abundance of rubbish and 

 leaves were collected in which the pest evidently passed the winter 

 in great abundance and in the spring the adults simply moved back 

 to the young growing trees and started the first colony of young. 



The writer finds that in the early spring the first forxiis to appear 

 are a few scattered adults. Following these is to be found usually 

 a rather heavy brood of the young which are sufficiently abundant 

 to seriously curl the first leaves. In a month to six weeks following 

 this a second colony arrives and in a like period a third and so on 

 until shortly before the leaves begin to fall. The later broods increase 

 in numbers where measures are not taken to check them. 



The writer has not been able to determine definitely with reference to 

 the actual number of summer broods, but those which he has followed 

 through seem to require from four to six weeks to complete their 

 growth. In a nursery where the pest is uninterrupted one can usually 

 determine from a single infested tree the number of times at which 

 the heavy broods arrive from the fact that beginning near the ground 

 is to be found a circle of curled leaves followed by fairly healthy foli- 

 age, succeeded in turn by another badly curled portion, and so on 

 to the top of the tree. 



From observations made before and after the first killing frosts this 

 fall, it has been found that the adults leave the trees and collect along 

 fence rows and in other protected places for the winter. The writer 

 believes this will be found to be true throughout this state at least. 



In reference to remedies for the pest it has been found impossible 

 to control it entirely by the application of sprays. After a number 

 of years of experience with spraying operations, the foreman of the 



