The evening times., 1899-07-28
GUARDING SHADE TREES
An Entomologisfs Views Regard
ing Arborage Protection.
Prof. Howard, of the Agricultural
Department, Publishes a Paper ON
the Subject of Insect Destructive
Operatfons-Vermin Enemies Of the
Forests of the National Capital.


without its splendid shade trees or with |
them shorn completely of their foliage"
exclaimed Prof. L. o. Howard. the ento-
mologist of the Agricultural Department.
Apropos the season, this is the month |
of the year when insect life gets in It's
worst pestilentil work on the trees
work that may be the precursor OF ca
lamity. If not a present pest. In 1885 the
elm-leaf beetle defoliated the English
elms in almost every low-lying town from
Charlotte, n c.. TO Albany. N Y. The
authorities of a number Of the towns took
alarm, and active remedial work was in
stftuted during the ensuing season. For
the intelligent forester Prof. Howard has
in preparation a most useful work on the
subject OF shade-tree insects. For the
edification of the average reader, however.
who is certainly interested in the preser-
walton of the foliage of the trees of this
city, the department has just republished
another paper by Prof Howard on the in
sect enemies Of shade-trees.
The stalwart naples and elms In La
fayette Square and on Fourteenth Street
have woefully suffered in years past from
these insects. This has been. say the en-
tomologists OF the Department OF Agri-
culture because of the neglect of the Park
Commissioners or their ignorance in re-
spect TO the remedy. The department Of
ficials invite a contrast, even at this time
of the year. OF the superior foliage OF the
trees in the grounds Of the Agricultural
Department with the tree foliage on our
streets and in our public parks. One has
only to observe the foliage of the trees
over the border of the Agricultural grounds
that is. the grounds OF the Smithsonian
Institution, which are under the supervis-
ion of the Interior Department-to note
the wonderful difference between the trees
that are protected from insects and those
which are not. The Agricultural Depart
ment has now in use within its own
I grounds steam spraying machine, which
| has been both successful and economical.
Concerning the foliage and destroying in
sects in the District Of Columbia, Prof.
Howard says:
The bagworm has been increasing for
a number of years. until it has become a
serious enemy TO shade and ornamental
trees. The white marked tussock moth, the
caterpillar of which has been for many
years the most serious of Shade-tree pests
| in Philadelphia, New York, and Boston, in
1895 appeared in such numbers as 10 be-
come a great Importance in Washington.
4 anu Inc Idll NeD-NOTiu was
more abundant in Washington and the sur
rounding country. These four insects are
the principal shade-tree defoliators in the
Eastern States. They are always present
and do a certain amount of damage each
| season. When an exceptional season comes,
! as IL did in 1895, city authorities seldom
find themselves prepared 10 engage in an
| intelligent and comprehensive fight The
so-called 'gloomy-scale' has long been on
L l,h in md
year it kills large branches and even entire
trees OF the silver NAPLES, which are so ex-
| tensively grown along the streets of this
city.
I'm Washington there are invariably two
generations of the eim-leaf beetle. The
beetles develop from the eggs laid by the
oyerwintered beetles themselves laying
their eggs in July. The adults issuing from
these eggs make their appearance in Au-
gust. The proper food of the larva is the
| rather young and tender leaves. If the
| work Of the first generation has not been
! complete and the trees have not been so
| nearly defoliated as to necessitate the
| sending out of fresh leaves, or II a period
of drought ensues after defoliation and
! prevents second crop Of leaves. the bee
! ties Of the first generation do not lay eggs,
but after flying about for time seek win
| ter quarters. This may occur as early as
the middle Of July. When. however de-
| foliation has been complete and has been
| followed by a second crop of leaves the
beetles of the first generation will lay their
eggs and second generation OF larva will
| develop upon this comparatively tender
! foliage. Where similar conditions prevail
in Washington and vicinity a third genera
tion of larya may develop, and / am con-
WINGED that even in Washington late-de-
veloping beetles OF the first generation
may hibernate
The only satisfactory safeguard against
| this insect is spraying the trees with an
arsenical solution. My experience in
Washington leads to the conclusion that il
is important to spray the trees once just
after the buds have burst. The spraying
is directed toward the overwintered beetle.
| If large proportion of these beetles can
be destroyed by poisoning the leaves which
| they eat not only will a great deal of leaf
perforation by the beetles themselves be
prevented. but the number of eggs laid
viii be very greatly lessened. A second
spraying should be conducted two weeks
later. This is directed against the larva,
majority OF which will perhaps be hatch
ed by that time or later. Two sprayings,
covering all the elms of a city. will be well
worth the expense. The substance may
be paris green, London purple or arsen-
ate of lead.
The white marked tussock moth at
tacks almost every variety of shade. fruit.
and ornamental trees. In the city of Wash
ington IT seems to select by preference the
poplars, naples, elms, alders, birches. and
willows. 1t is also found here. on apple
cherry, pear, plum, peach, locust, box,
elder, ash, catalpa, rose, horse chestnut,
persimmon, sycamore, and mulberry. This
| insect passes the winter In the egg state
J The over-wintering eggs are laid by the
female moth in the latter part of Septem-
Der. They are seen at a glance. owing to
their pure white color, and remain Con-
spicuous on the trees until spring. The
caterpillars hatch in Washington in April
or May. They cast their skin FIVE times,
exhibiting a different character after each
molt The newly Matched young feed on
| the under surface of the leaf, eating of
and producing a skeletonized appearance.
The adult insect presents the rather unusu-
| al phenomenon of a winged active male
and a wingless, absolutely degraded fe-
| male. There are certainly two and prob
ably three, annual generations in Wash
| ington. Spraying, as described, is the
| remedy.
| THE fall web-worm is associated with
| the white-marked tussock moth in its dam
| age to the shade trees of Washington. This
| insect was abundant here in 1895. 1t is an
| almost universal feeder and the records of
this Bureau list about 120 species Of shade
and ornamental trees. as well as fruit trees,
upon the leaves of which ii feeds. In the
District Of Columbia and north to New
York city there are two generations annu-
ally. 1t hibernates as pupa within CO.
coon attached to the trunk of its food
plant, or to treeboxes. fences, rubbish, and