14 BULLETIN 899, U. S. DEPARTMENT OF AGRICULTURE. 
method was to use the putty knife alone, and with it thoroughly work 
up and renew the old surface. 
After bands have remained on trees for one or more years it is 
often advisable to resurface with the special gun. The bands shrink 
in dimensions after being applied more than a year so that a nozzle 
of the same size as was originally used fits over them, thereby apply- 
ing a thin smear of the material to all exposed sides. One pound of 
the material will resurface from 25 to 30 linear feet against 10.5 at first 
application when a nozzle J by J inch is used in each case. This is 
the most efficient method of resurfacing known and leaves the bands 
in practically the same condition as when they were first applied. 
BEHAVIOR OF CATERPILLARS BENEATH GIPSY MOTH TREE-BAND- 
ING MATERIAL AND ITS EFFECT UPON THOSE CROSSING BANDS. 
The first samples of gipsy moth tree-banding material were tested 
in 1915. At that time the consistency of the material was quite stiff 
and caterpillars frequently crossed the bands in areas that had partly 
dried or filmed over on the surface. The idea as conveyed by the 
Germans in 1912, when a quantity of raupenleim was imported for 
experimental purposes, was that the nun moth {Lymantria monacha 
L.) and the gipsy moth (Porthetria dispar L.) were barred beneath 
the bands from their dislike of the tar odor emitted by the compound. 
Some experimenting and many observations have been made to as- 
certain if the guiding sense in preventing caterpillars crossing bands 
was smell or touch. Bather hard and soft mixtures with varying de- 
grees of odors and substitutions for the coal-tar odor have been made 
with pine tar and other ingredients. Whenever the material was 
quite stiff, regardless of the odor, the caterpillars frequently crossed 
or rested on or near the bands (PL VI). Gipsy -moth caterpillars 
were seen repeatedly to go up to bands and touch them either with the 
head pencils of hairs or mouth parts, or walk into them. If the sur- 
face of the bands was soft, oily, greasy, or sticky, affording discom- 
fort to the touch or making it impossible to secure a footing, the 
caterpillars usually turned back. As many as 97 to 99 per cent of 
the caterpillars in a heavy infestation were barred on some trees by 
the soft, oily, gipsy moth tree-banding material used in 1919 (Pis. 
IV, V). 
Many caterpillars, especially the younger stages of the gipsy moth, 
in attempting to cross or when blown into the bands by the wind, 
quickly die from the effects of the material covering the ventral por- 
tion of the body and entering the spiracles. The percentage of larvae 
killed in this manner is very high. There were from 150 to 200 small 
caterpillars dead in the oily surface of each of a few bands in a heavy 
infestation in 1919 with from 1,500 to 2,000 barred by the same bands. 
Large larvae of several species are also killed from effects of the ma- 
