﻿2 BULLETIN 1142, V. S. DEPARTMENT OF AGRICULTURE. 



phere, as in a room, the odor is quite pungent, irritating the mucous 

 membrane to a considerable degree. 7 



REASONS FOR INVESTIGATION. 



In the course of the preparation and use of the tree-banding ma- 

 terial, as -well as of the last of the raupenleim, by members of the 

 gipsj^ moth force, the question as to what constitutes the barrier factor 

 in the band arose ; that is to say : What element or elements in the band 

 halted the caterpillars in their attempted ascent to the foliage? Was 

 it the exhalation, or odor (chemical property) of the material; or 

 "was it its softness, or viscidity (plvysical property) ? Since the bands 

 did not function as well in cooler weather or as they aged, was their 

 decline in power or efficiency at such times due to their decreased vis- 

 cosity, or firmer consistency; or was it due to the lessened odor? 

 These questions had a practical bearing on the development of an 

 efficient barrier, and attempts were made to obtain the desired in- 

 formation by means of field observations. These, however. Avere not 

 successful; indeed, they served only to develop decided differences 

 of opinion. Nor was there any help to be had from European 

 sources. Mr. L. H. Worthley, for instance, who spent the summer of 

 1912 in Europe investigating gipsy moth conditions for the Bureau 

 of Entomology, reported, on his return, that the forest authorities of 

 Saxony and Bavaria regarded the odor as the effective element, or 

 factor, in the band. But this information lacked applicability; for, 

 aside from. the fact that these foresters dealt exclusively with raupen- 

 leim, a material possessing a somewhat stronger or more pungent 

 odor than the gipsy moth tree-banding material, their views were 

 based largely, if not entirely, on the behavior of another species of 

 insect, namely, the nun moth. It was possible, certainly conceivable, 

 that the two species might differ in their reaction; and an investiga- 

 tion of the literature on the subject disclosed the propriety of the 

 assumption, for, according to Judeich and Nitsche (4, V- 8^5, 888), 

 such a difference of behavior exists, at least in the case of the nun 

 and pine 8 moths, the caterpillars of the former, according to these / 

 authors, avoiding or shunning tine raupenleim to a far higher degree 

 than those of the latter. The uncertainty, it might be added, was 

 somewhat further increased, in view of the further statement of 

 Judeich and Nitsche (ibid.) that "Die Nonnenraupen vermeiden jede 

 Beriihrung des Leimes * * *," by the statement of Ratzeburg 

 (.9, p. 52) to the effect that some of the caterpillars of the nun moth 

 will brave the odor of tar. Because, therefore, of the lack of definite 

 knowledge and the uncertainty and of the practical bearing that such 

 knowledge had on the elaboration of an efficient barrier, it was 

 deemed advisable to investigate the matter. 



THE PROBLEM. 



That the odor of the material exercises a restraining influence 

 could not be doubted. Neither, on the other hand, could one with a 



7 The term "odor" is used here in the common or ordinary (and older) sense, inclu- 

 sive of the irritating quality of the material as perceived by the nasal mucous membrane. 

 Properly speaking, of course, the latter property of materials is not generally olfactory 

 (5, p. 165, 169). In this connection the writer wishes to thank Prof. G. H. barker, pro- 

 fessor of zoology, Harvard University, for the courtesy of allowing him to read portions 

 of bis forthcoming book dealing with the chemical sense in vertebrates and for other sug- 

 gestions. 



8 Bomhyx pini L. (" der Kiefernspinner "). 



