1896.] ENTOMOLOGICAL NEWS. 177 



DEPARTMENT OF ECONOMIC ENTOMOLOGY, 



Edited by Prof, JOHN B, SMITH, Sc.D., New Brunswick, N. J. 



Papers for this department are solicited. They should be sent to the editor, Prof. John 

 B. Smith, Sc.D., New Brunswick, N. J. 



" Raupenleim" and " Dendrolene." As a result of the experience gained 

 during the season of 1895 in the use of these materials I spoke rather 

 positively concerning their usefulness on various occasions. I have seen 

 no reason to change my conclusions as to their value for the purposes 

 recommended, but it has been found that it is not desirable in all cases to 

 leave the material on continuously. In the case of the peach orchard 

 upon which experiments were made, the story came after mid-Summer 

 that the " Dendrolene" had killed the borers in the trees. I was scarcely 

 ready to credit that at the time, but I am much more ready to do so now. 

 At the time mentioned there wss no sign of injury to any of the trees 

 from either " Raupenleim" or " Dendrolene," nor was there any in Sep- 

 tember, at which time the " Raupenleim" was pretty well dried up, inef- 

 fective as a covering or for any other purpose, while the " Dendrolene" 

 was in good condition and fully protective for all practical purposes. It 

 seems that this continuous covering is not of advantage to thin-barked, 

 rapidly growing trees, like a young peach. It is found that now, just 

 about the time the trees are starting, that there has been a decided check 

 to growth at the point where the "Dendrolene" has been applied. The 

 outer layer of bark has become lifeless and discolored, while beneath, 

 that upon the trees, is still perfectly healthy. The trees referred to are 

 peach trees, four years old, thrifty and growing rapidly. The treated 

 trees are just as healthy, to all appearances, as those not treated, and, 

 except for the death of the outer layer, no injury has been sustained, but 

 this indicates the necessity of a little care in the use of the material. If 

 it is applied on peach trees in the Spring against the borer, it should be 

 mixed with an equal proportion of dry earth, which will leave it just as 

 effectual as a covering to keep out the borer, and will deprive it of some 

 of its penetrating qualities. The crust thus formed can be easily scraped 

 off after mid-Summer, when danger from borers is over, and this will 

 avoid the danger of injury to the bark. The " Kaupenleim" had a simi- 

 lar, though much less marked effect, due to the fact, probably, that it is 

 much more viscid, and dries up in a comparatively short time instead of 

 simply getting thin under the influence of heat, as does the "Dendro- 

 lene." On apple trees, where this same material was applied liberally to 

 keep out the borers, it was perfectly effective, and not the least trace of 

 injury of any kind was found upon the tree or bark. Experiments will 

 be continued with the material in the direction of mixing it with land 

 plaster or other substances, to reduce its action upon the trees. I am 

 just as much convinced of its usefulness as ever, but wish to suggest to 

 those who intend experimenting with it the desirability of caution in 

 certain cases. 



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