﻿BARRIER FACTORS IN GIPSY MOTH TREE-BANDING MATERIAL. 15 



pillar in a comparatively short time, even on days of moderate, tem- 

 perature. In case of actual contact, however, injury may be from 

 an additional source — from the penetration of the material through 

 the skin. 17 



The irritation or " burning " caused by the gipsy moth tree-band- 

 ing material, as a result of contact, may therefore aid in repelling the 

 caterpillars, especially if contact is with delicate and sensitive parts, 

 such as the mouth parts. Again, since the latter are organs of taste, 

 and in certain adult Lepidoptera at least the tarsi also act as such 

 (7, p. W2-W3; 8, p. 80-81), the sense of taste may be a factor. These 

 considerations, however, should not affect the conclusion that the 

 viscous, or physical, condition is the more important, or primary, 

 barrier factor in the -band as it ordinarily functions, which may be 

 said to have been clearly demonstrated and which is borne out, so far 

 as can be judged, by observations' in the field. Indeed, since the 

 head, the head appendages, and the legs of caterpillars seem to be 

 well adapted for receiving olfactory stimuli (6, p. 76) , we may per- 

 haps also see in the rather rapid withdrawal of such parts the action 

 of odor and thus additional evidence, or a confirmation of the other 

 and more obvious conclusion, namely, that the two factors, i. e., the 

 soft or semiviscid or viscous condition of the material, and the odor, 

 or exhalation, of the material, are the chief factors which make the 

 gipsy moth tree-banding material the efficient barrier that it is. 



LITERATURE CITED. 



(1) Burgess, A. F., and Griffin, E. L. 



1917. A new tree-banding material for the control of the gipsy moth. 

 In Jour. Eeon. Ent, v. 10. no. 1, p. 131-135, pi. 6-7. 



(2) Collins, C. W., and Hood, Clifford E. 



1920. Gipsy moth tree-banding material : how to make, use, and apply it. 



U. S. Dept. Agr. Bui. 899, 18 p., 4 fig., pi. 1-7. 



(3) Forbush, E. H., and Fernald, C. H. 



1896. The gipsy moth (PortJietria dispar Linn.). Mass. State Bd. Agr. 

 Kept, p. xii+495+c, 35+2 fig., 66 pi., 5 maps. 



(4) Judeich, J. F., and Nttsche, H. 



1895. Lehvbuch der niitteleuropaischen forstinsektenkunde. Bd. II 

 (Wien), p. xxii +737-1421, fig. 216-352, Taf. V-VIII. 



(5) Luoiani, L. 



1917. Human physiology. Vol. IV. The sense organs. Trans, by F. A. 

 Welby ; ed. by G. M. Holmes, p. x+519+4, 217 fig. London. 



(6) McIndoo, N. E. 



1919. The olfactory sense of lepidopterous larvse. In Ann. Ent. Soc. 

 Amer., v. 12, no. 2, p. 65-84, 53 fig. 



(7) Minnich, D. E. 



1921. An experimental study of the tarsal chemoreceptors of two 



nymphalid butterflies. In Jour. Exp. Zool., v. 33, no. 1, p. 

 173-203, 6 fig. 



(8) . 



1922. The chemical sensitivity of the tarsi of the red admiral but- 



terfly, Pyrameis atalanta Linn. In Jour. Etxp. Zool., v. 35. no. 

 1, p. 57-81, 3 fig. 



(9) Ratzeburg, J. T. C. 



1840. Die forst-insekten. Zweiter theil. die falter, p. v+252, Taf. 

 I-XVI. Berlin. 



17 Severe " burning " may result if the material is placed upon and is allowed to pene- 

 trate the human skin. 



