38 



many (at an estimate) of the pupa? as were to be found upon any one 

 of the elms. It must be remembered that but a small portion of the 

 circumferential growth of the top of each elm overhung the horse- 

 chestnut. Perhaps the portions of the three tree tops so overhanging 

 would constitute a third of the arc of a circle. It at once becomes evi- 

 dent that in the case of these three elms nothing like 60 per cent of the 

 larva? descended the trunk of the tree upon which they were raised, 

 and, In fact, that only about one-half of this percentage was correct in 

 this case. Fully 70 per cent must have dropped from the limbs. 



I do not pretend to say that this instance was not unusual, but that 

 it demonstrates the vast superiority of spraying over all other means 

 of fighting the elm leaf-beetle more forcibly than it has previously 

 been shown can not be doubted. 



Mr. Marlatt read the following paper : 



INSECTICIDE SOAPS. 



By C. L. Marlatt, Washington, D. C. 



The decided insecticide value of the so-called whale-oil (more prop- 

 erly fish-oil) soaps against scale insects particularly has been fully 

 demonstrated in the last few years in the work against the San Jose 

 scale, and has fully substantiated Professor Oomstock's early recom- 

 mendation of this means of controlling scale insect pests. The merit 

 of these soaps is not only in their effectiveness as insect destroyers, 

 but from their being entirel}' without injurious effect on the treated 

 plant. In this respect they are perfectly safe in the hands of any per- 

 son, in contradistinction to all oily washes, which are very liable to be 

 injurious in greater or less degree, although the injury may be insig- 

 nificant, or perhaps not apparent immediately, or during the first sea- 

 son. As pointed out at a previous meeting of this association, and 

 also in the bulletin on the San Jose scale issued by the Division of 

 Entomology, United States Department of Agriculture, the use of soaps 

 is attended with certain hitherto unavoidable difficulties. It seems 

 impossible to secure with any degree of certainty soaps which may be 

 depended upon to behave in the same manner when dissolved for appli- 

 cation as a paint to trunks of trees, or in a spray for application to the 

 entire plant. During the past two years we have been making a strong 

 effort by correspondence and personal interviews with leading soap 

 makers of Washington, Philadelphia, and Xew York to get a suitable 

 soap, uniform in composition and behavior, which could be relied upon, 

 but so far with indifferent success. The leading Washington soap maker 

 after one trial refused to bother further with fish-oil soaps, on account 

 of the disagreeable nature of the oil and the vile odors engendered 

 while working with it. Some half dozen samples each have been 



