338 AGRICULTURE OF MAINE. 



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 expanding foliage. 

 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 leaves, twigs, and branches. However thoroughly the 

 work may be done, some of the "lice" are almost sure to escape 

 destruction, owing to the difficulty of forcing the spray between 

 the unfolding leaves, more or less covered with hairs, where 

 some of the insects will have penetrated. A subsequent treat- 

 ment 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 on the lower surface of the curled 

 leaves will not be hit by the spray. Repeated applications must 

 be made, therefore, as necessary to keep the insects under con- 

 trol. 



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

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

 wash (Formula 4). 



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

 must be employed, as strong tobacco decoction, 15 or 20 per cent 

 kerosene emulsion, or whale-oil soap (Formulas 7, 9, 11). 

 Since aphids secure their food by sucking up sap from within 

 the plant, none of the arsenical poisons would be effective. 



