MAINE AGRICULTURAL EXPERIMENT STATION. 21 



terminal twigs (fig. 30). With young trees especially, which 

 are seen to be heavily stocked with the eggs, the latter may be 

 in part removed during the work of pruning, and the prunings 

 should be collected and burned. 



The insects in the egg condition are frequently distributed 

 on nursery stock ; therefore, if in planting trees this stock be 

 well pruned and the prunings destroyed, the establishment of 

 the aphids in young orchards may be often prevented or delayed. 



Winter spraying for destruction of eggs. — When lime-sulphur 

 is used for scale insects, some of the aphid eggs are incidentally 

 destroyed. Experiments in certain localities on old trees where 

 the rough bark affords protection, however, would indicate that 

 a winter spray applied for the eggs alone is hardly warranted 

 by results obtained. 



Spring and summer treatments. — Effective work in control- 

 ling these insects may be done in the spring just after they have 

 hatched from eggs and have collected on the tips of the buds 

 showing green and while the buds are compact and before the 

 aphids have an opportunity to seek the protection of unfolding 

 foliage but are exposed on the surface of the buds. Trees 

 seen to be badly infested at this time should be thoroughly 

 sprayed, taking pains to wet as completely as possible all parts 

 of the buds, twigs, and branches. However thoroughly the 

 work may be done, some of the "lice" may escape destruction. 

 A subsequent treatment in the course of a week should usually 

 be made, especially if the first application is seen to have been 

 unsatisfactory. 



After the foliage is well out and more or less distorted from 

 the presence of the aphids, effective spraying is quite difficult, 

 since many of the insects are on the inner surface of the curled 

 leaves. Much can be done however with high pressure and a 

 drive nozzle. 



Spray mixtures. — The lime-sulphur wash for the destruction 

 of winter eggs is made according to the usual formula for the 

 wash. 



After the trees are in foliage, a more dilute contact insecticide 

 must be employed, as black leaf 40 or other good tobacco decoc- 

 tion, kerosene emulsion, or whale-oil soap. Since aphids secure 

 their food by sucking up sap from within the plant, none of the 

 arsenical poisons would be effective. 



