The Portland daily press., 1895-09-28


army Of them went into their winter
quarters, with such an evident intention
of coming forth next spring in the shape
of a swarm Of moths, That would repro
duce themselves hundred fold on the
leaves of the elms, that no little alarm
has been felt for the safety of the elms
next year.
It is interesting to notice, if you have
not done so. how numerous are these
cocoons at the present time on the trunks
of the elm trees of this city. The broom
and the brush of energetic housewives
have removed most of them from the
houses and fences but nothing has dis
turbed them on the tree trunks. They
line the creyices in the rough bark by the
score, from the ground far up into the
branches and apparently give ugly
promise of what will happen when they
come to life again next spring.
But if you examine these ,ocoons care
fully and cut them open with knife you
often find that the pupa is but thin
empty she'll, and of course devoid OF life.
So many of the pupae in these cocoons
have thus been destroyed chat after a
casual examination you might suppose
that there were more dead than living
cocoons on the trees.
In the fifth report of the U. S. Ento-
biological Commission. in an article
about ssInsectivorous orParasitic Insects, !"
the following statement is MADE:
aWhile the undue increase Of forest in
scots is largely prevented by insectivorous
birds. their numbers are especially re-
duced by the attacks of parasitic or car
nivorous insects. Of these the most eff
cient are the ichueumon flies, which are
wasp like insects, forming large group
Of the order Hymennoptera OF these
ichneumon flies there are probably from
1000 to 5000 species ;"
The dead pupae in the cocoons in this
CITY above mentioned are the result of
the attacks of these parasitic insects, the
ichneumon flies. A Portland man has
been making special study this summer
of this caterpillar pest and Its parasitic
enemy. This man is Mr.. Gilbert NJ
Dinsmore, the observer at the Portland
Observatory All through the summer he
has been studying these interesting in
scots. He believes that the caterpillars
are a serious menace to our beautiful
shade trees By counting the cocoons on
a certain area of tree trunk, on Munjoy
Hill. he estimated that on that tree alone,
there were at least 1000 of them. He says
that the English sparrows or any other
birds. will not eat these caterpillars, be-
cause of the hairy tufts and that the only
hope of restraining them within due
bounds is either from the attacks OF the
ichneumon flies or by some special human
effort to rid the trees of the cocoons be-
fore the moths shall come forth in the
spring.
He has observed insects for years and
saws that with the advent of the cater
pillars, the ichneumon flies increased till
they swarmed in much greater numbers
than he had ever before seen them. In
July and August he spent good deal OF
time in Watching these flies in their at
tack upon the caterpillar. Our Illus
traJion gives type of the iohnoumon fly
This is the natural size of this species,
which is named Rhyssa. The long fila
lnents that project from the abdomen are
not sting, though they deal death and
destruction to the caterpillars. They are
the ovipositor of the fly; that is, the egg
layer With this frightfnl weapon tie
fy punctures the body Of the caterpillar