150 MONTANA EXPERIMENT STATION. 



to pursue them with the ever ready spray pump and nozzle, before 

 they begin to fasten the leaves together. The disadvantages of 

 spraying at this time are : that it is rather difficult to get a thorough 

 coat of poison on the under side of the leaves where the worms are 

 now feeding, that the pubescence of the under side prevents the 

 spray from adhering as closely and uniformly as above, and finally 

 that the fruit, where the trees are bearing, is now ripening in many 

 cases and there is more or less danger of having a coat of poison up- 

 on it when it is ready for market ; the application can be timed, 

 however, in most cases so as to avoid this trouble. A coat applied 

 when the eggs were still unhatched would cleave sufficiently to make 

 life very uncertain for the resulting larvae. The advantages of 

 spraying at this time are : that the leaf buds have ceased to grow 

 and the spray is good as long as it retains its poisonous properties, 

 since there is no danger of the trees outgrowing it and making 

 fresh feeding grounds for the worms as is the case with the earlier 

 applications. In this advanced stage the foliage is also very resis- 

 tant and the mixture can be applied at a greater strength than for- 

 merly, which up to a certain limit, makes it much more adhesive. 

 As a general rule where trees are infested by this insect keep the 

 the early buds and blossoms sprayed by all means, whether it re- 

 quires one, two, or three applications, and spray later if the insect 

 is still present. 



HOW TO SPRAY. 



This has been widely discussed in bulletins dealing entirely with 

 the subject of spraying and requires only a word here. As a 

 ■complete and even distribution of the spray is the principal thing 

 to be attained in dealing with this insect a Vermorel, or similar 

 nozzle that will give a wide and fine distribution to the liquid, 

 should be used. In putting on the first spray the operator should 

 not confine his attention to the buds alone but should give the 

 leaves a thorough coating, since the object is not only to keep the 

 insect from doing immediate damage, but to kill it if possible. 

 This of course should be done from an elevated platform, or by 

 means of a long bamboo stick or rod attached to the nozzle so that 

 the topmost branches can be reached and the upper side of the leav- 

 es thoroughly covered. In dealing with the summer brood it is 



