100 THE CONNECTICUT POMOLOGICAL SOCIETY. 



nigh an impossible one. But we have made possible so many 

 impossibihties that even this might be surmounted, were it not 

 for the fact that the young do not come all at one time and 

 that by the time he last one is born the first lot are almost ready 

 to breed in turn. Now, while we can very easily kill the 

 crawding larvae without harm to tree or foliage, the same 

 mixture would not be equally effective against the breeding 

 adults and we ha\'e nothing yet that will kill adults without 

 harming foliage and even shoots and branches. To get the 

 insects in the larval stage, therefore, would mean spraying at 

 least every other day for a period of at least three weeks — an 

 obvious impossibility in an orchard. 



We are reduced therefore to dealing with the insect in its 

 dormant state wdiile the trees are themselves dormant and free 

 from foliage. And we must reach a very soft, helpless insect 

 under a very tough scale covering, closely applied to the sur- 

 face of the tree. Easy enough to kill the insect; but to get at 

 it first is the difficulty. The material forming the scale resists 

 penetration by all ordinary caustic and acid applications not 

 also dangerous to plant life, and we must get at it, therefore, 

 by some substance that acts on the insect with a margin of 

 safety for the plant. 



We have at our disposal the choice between corrosives, that 

 act first on the scale covering and then on the insects, and 

 penetrants that leave the scale intact and forcing their way 

 through, act directly upon the insects. 



Types of the first are whale oil soap and the lime and sul- 

 phur mixtures; types of the second are the mineral oils, crude 

 or refined, undiluted or mixed with water. 



Whale oil soap has had its trials, its limitations are well 

 understood and while it has done and can do satisfactory work, 

 the cost has excluded it from practical consideration of late 

 years. 



The lime and sulphur ccmibinations are all of them ex- 

 tremelv caustic, all of them absorb water from the surface on 

 which they are applied, and act first by loosening the hold of 

 the scale covering upon the surface of the plant. Jtist what 

 happens afterward is yet a matter of some question : but at all 

 events slow decomposition of the sulphide of lime begins and 



