MONTANA EXPERIMENT STATION. 



21i 



Figure 4. 'Wingless viviparous female on left; oviparous female on riglit — 

 ■greatly enlarged. (Sanderson, Vi Ann. Kept. N. J. Exp. Station). 



or the other of the mid-rib. The lice live inside of the curled leaf, a 

 fact which has much to do with the difficulty in controlling them 

 with insecticidal spi.ays. 



There is some reason to believe that the presence of the lice in 

 large numbers on a tree has the effect of keeping the sap in the 

 tree late in the fall, thereby making it more liable to injury by 

 cold weather. It 's certain that badly infested leaves on the ends of 

 the new growth often fail to mature and remain on the tree through- 

 out the winter. This is often noticeable on trees in the nursery row. 



The general injurious effect of the lice is to check the normal 

 growth of the tree. This office has many records of this effect in a 

 serious degree. 



We have never found this louse occurring in great numbers on the 

 young buds in the spring as is often the case with "Fitche's apple 

 aphis." As a rule, only a few scattering lice are to be found 

 early in the season, and our exeprience has shown that frequently 

 only here and there a tree will be found infested in the spring of the 

 year, though as the season progresses the lice will gradually spread 

 throughout the orchard. 



