April, '21] PETERSON.- PARADICHLOROBENZENE 155 



Mr. Alvah Peterson : The majority of the larvae are located above 

 the point where the large roots branch from the tree. Worms below 

 this point are few in number and are rather difficult to kill. 



Mr. George A. Dean: Have experiments been carried on in con- 

 nection with the woolly aphis ? 



Mr. Alvah Peterson : Mr. Blakeslee has shown that this material 

 cannot be used on apple trees, as it seriously injures them. 



Mr. William Moore: Many years ago, I think in the 8U's, Hilgard 

 of California pointed out that the phenomenon of adsorption is very 

 important in the treatment of underground insects. 



I would like to ask if Mr. Peterson has carried out any experiments 

 on the adsorption of paradichlorobenzene by the soil? 



Mr. Alvah Peterson : I have not. 



A Member : I would like to ask what results have been secured with 

 orthodichlorobenzene ? 



Mr. Alvah Peterson: Orthodichlorobenzene is a liquid and our 

 experience shows that it is injurious to peach trees, and should not be 

 used. We killed more than one hundred trees this summer by using it. 



Mercuric chloride gives considerable promise of being an effective 

 insecticide against the young borers in the trees. It was used in the 

 same way that it has been applied in Canada for the control of the onion 

 maggot. Further experiments will be conducted along this line. 



Mr. H. F. Deitz: Where can paradichlorobenzene be purchased? 



Mr. Alvah Peterson: From the Hooker Electro-Chemical Co., 25 

 Pine St., New York City; The Niagara Alkali Co., Niagara Falls, N. Y., 

 or E. C. Klipstein & Sons Co., 344 Greenwich St., New York City. 



Mr. a. L. Quaintance: I have been very much interested in the 

 experiments reported by Mr. Peterson. They conform so closely to 

 comparisons obtained by the Bureau of Entomology, that the members 

 may be interested to know that there is available a publication on this 

 subject and the treatment has already obtained large commercial use. 

 It has been used extensively in the Ozark region of Missouri and Arkan- 

 sas. In the peach belt in Georgia it has now been tried for two or three 

 years on a large commercial scale, and we are in a position to judge 

 somewhat of its effectiveness and its likelihood of injuring the trees. 

 To date we have had no serious complaint of tree injury ; on the other 

 hand, we have had numerous assurances that this was the long-sought 

 treatment for the peach tree borer. 



President Wilmon Newell : The next is a paper by Mr. Glenn W. 

 Herrick. 



