Vol. LV. No. 2430. 
NEW YORK, AUGUST 22, 1896. 
$1.00 PER YEAR. 
BORERS IN FRUIT AND SHADE TREES. 
“RAUPENLEIM” AND “ DENDROLENE.” 
The Real Value of These Substances. 
For many years, an insect lime—“ Kaupenleim ” 
(caterpillar glue)—has been largely used in Germany 
to protect trees from the attacks of certain insects, 
and to prevent their being injured by stock or deer 
during the winter. Recently, this substance has been 
introduced into this country, and is now on sale as 
Ermisch’s Caterpillar Lime. It has been quite ex¬ 
tensively used by the Gypsy Moth Commission in 
Massachusetts, and others have tested it on a small 
scale. It is a very dark-colored, butter-like sub¬ 
stance, with a strong, tarry odor. It closely resem¬ 
bles axle grease, and is, doubtless, some product of 
crude petroleum. It is to be applied to the trunks of 
trees in a thick coat, with a paddle or trowel, and 
then evenly distributed with a stiff brush. As it is 
rather an expensive material (costing from 10 to 15 
cents per pound, plus freight, depending upon the 
amount bought), Prof. J. B. Smith, of the New Jersey 
Experiment Station, in the winter 
of 1894-5, asked Prof. Mason, a 
chemist, to make some similar, 
but cheaper, material. The re¬ 
sult was that an American prod¬ 
uct called “ Dendrolenc,” was 
produced, and is now on sale by 
the Bowker Fertilizer Co. It is 
a Standard Oil Company’s product 
from crude petroleum. 
Dendrolene differs from the 
German product in being much 
lighter in color and nearly odor¬ 
less ; it is somewhat thicker un¬ 
der ordinary temperature, and is 
thus not quite so readily manip¬ 
ulated on the bark, in our experi¬ 
ence ; it gets softer under the 
heat of the sun, and shows more 
tendency to run. Both sub¬ 
stances, being mineral products, 
will not become rancid, and will, 
doubtless, keep all right for 
years. 
With us, the Raupenleim is 
easier to apply, remains as a 
thick coating longer, that is, 
shows less tendency to run, but 
it has more tendency to form a 
very thin, hard film over the 
surface ; the Dendrolene costs 
considerably less, from 7 to 10 
cents per pound with the freight 
prepaid. Not enough experiments have been carried 
on with both substances, as yet, to settle definitely 
which one is the better adapted for the purposes in¬ 
tended. The Gypsy Moth Commission found that 
Raupenleim, obtained at different times, varied con¬ 
siderably in its efficiency, indicating that its com¬ 
position may vary ; it would not be surprising if both 
substances varied in their chemical composition some¬ 
what. And this fact may, in some degree, account 
for the recent reports of injury to trees from their 
application. When properly applied, there seems to 
be, as yet, no authentic evidence of either substance 
having killed or severely injured fruit or forest trees, 
either in Europe or in this country. Where buds are 
covered they die, but when applied, as intended, on 
the bark of the trunk or larger branches, the only 
injury resulting, so far as recorded, is a slight one to 
the outer layer of the bark ; where the bark is scraped 
off too much before applying, more serious injury is 
very liable to occur. 
If these substances, or something similar, come to 
be recognized as important and effective additions 
to our insecticide battery, and I believe that they 
will, their use will, probably, be limited principally 
to preventing the ascent of insects or the entrance 
and, possibly, the exit of borers. From the experi¬ 
ments thus far recorded in this country, we are not 
yet entirely satisfied of the efficacy of either substance 
for these purposes, but the indications are, certainly, 
very promising. 
Our experiments have, thus far, been confined, 
principally, to their effectiveness in preventing the 
peach borer from getting into the trees. Raupenleim 
was applied to young trees last season, and the re¬ 
sults of our examination of the treated trees this 
year, gave some very important indications which we 
shall await another year’s experiments upon before 
publishing. With the exception indicated above, our 
trees were not injured in the least by the application. 
This year, we are testing both products, side by side, 
and so far, we can see but little difference in their 
action. Neither is so injurious to the bark as white 
paint (especially if Paris-green be added to the paint) 
or tar. We have found that applications which would 
not injure thrifty trees that have been set, at least a 
year, will injure and may kill trees that have been 
set the same spring or the fall before the application 
is made ; this is an important point, and our observa¬ 
tions apply to peach trees which are reported as hav¬ 
ing been severely injured, by some correspondents. 
It may be well to say here that, for the peach borer, 
it is not necessary to apply the substance until about 
July 1, in New York State, as most of the eggs of the 
insect are not laid until after July 15. For the apple 
borers, the application must be much earlier, probably 
by May 1. Either substance will retain its preventive 
qualities for many weeks. It is doubtful whether the 
exit of these large borers can be prevented by apply¬ 
ing the substances earlier ; there is some evidence to 
show that the exit of the smaller borers like the Shot- 
hole, peach and plum borers, can be thus prevented. 
These last-named borers are hard insects to get at, 
and if these insect limes do prove effectual, either to 
prevent their exit or entrance, it will be a great boon 
to many attiicted orchardists. 
So far as our observations go, we are not very favor¬ 
ably impressed with the effectiveness of either Den¬ 
drolene or Raupenleim as preventives of the ascent of 
caterpillars, etc., when put on as bands on the trunks 
of the trees. Only a few hours after the application 
of Raupenleim to one of our peach trees, we saw an 
army worm traverse it for over a foot without any 
discomfort. We have also seen smaller insects freely 
cross bands of both substances on apple trees. One 
report has come to us that Dendrolene was quite in¬ 
effectual in stopping the canker worms in western 
New York this year; but then they have had canker 
worms there this year to an extent almost beyond 
one’s imagination ; hundreds of acres of orchards were 
entirely stripped by the vast hordes of hungry worms. 
Where such insects occur in such numbers, several 
have reported that the Raupenleim was ineffective. 
There is need of further experimentation with these 
substances against canker worms, climbing cutworms, 
and similar insects climbing trees before they can be 
recommended with entire confidence. 
A very important point in connection with the ap¬ 
plication of either Raupenleim or Dendrolene for 
borers or ascending insects, is 
that the material must be put 
on at least one-quarter inch 
thick ; applied thinner than this, 
it soon dries out, and is thus 
rendered ineffective. 
Many queries reach us in re¬ 
gard to borers affecting maple 
shade trees. There are several 
different insects which are maple 
borers ; a very destructive kind 
was imported a few years ago 
into New York City, and is slowly 
spreading in all directions. Where 
these maple borers confine their 
work to the trunk, it may be 
practicable to apply the Raupen¬ 
leim or Dendrolene to prevent 
the mother insect from laying 
her eggs. The borer which is 
making sad havoc in maple trees 
in New York City parks, and in 
surrounding localities, however, 
does not confine its work to the 
trunk, but kills the larger 
branches. It would usually be 
impracticable to treat the 
branches of these trees as well 
as the trunk. It is thus doubtful 
if either of the substances under 
discussion will prove practical 
aids in our warfare against 
maple borers. 
Mr. E. B. Southwick, entomologist of the Central 
and City Pai’ks of New York City, has had much ex¬ 
perience in treating borers. He collects all affected 
or broken branches, carefully removes and kills all 
the grubs he can find, then burns the blanches. In 
1893, he and his assistants spent three months collect¬ 
ing and destroying the grubs of the newly-imported 
maple borer mentioned above. He says that the 
effects on the numbers of the borers the next year, 
were very evident. All the smaller trees in the parks 
are carefully examined, and when a burrow is found, 
bisulphide of carbon is injected into it from a common 
oil can, and the hole quickly closed with putty ; this 
carbon is sure death to all living things in the burrow. 
Mr. Southwick has also found this a very effectual 
method against the apple-tree borer and all other 
borers whose burrows can be found ; often the bur¬ 
rows are readily found from the matter the grubs eject 
from the mouths of their tunnels. 
In brief, the German Raupenleim and its American 
counterpart, Dendrolene, so far as they have been ex¬ 
perimented with, give results which strongly indicate 
“THE AGENT’S SHARE!” “ONLY A YEAR!” Fig. 174. See page 568. 
