, 1891-08-15

A Description oil Plant Lice by the
University chronological.

university EntOmOlOSlst
Prof. F. j. Niswander, entomologist OF
the agricultural experiment station of the
Wyoming university, has issued a bulletin
descriptive of the common pests, plant
lice. and giving formulas of checks against
their Tavagcs. Portions of the builetin
arc as follows:
Perhaps there is no family of insects
that that is more widely distributed, does
more damage to vegetation and Is more
generally known than plant lice (.AphidH).
They are great pests in the Cr%cenhOuse,i in
the garden, and do great damage to our
forest, shade and fruit trees, causing the
foliage to curl up and drop from the trees.
The members of this family dc not only
iced upon the foliage OF plants, but many
species attack the branches and trunks Of
trees, while others live entirely upon the
roots.
Not n cottonwood has escaped them,
and the damage they are dong to the
trees is considerable. The two species Of
the lice that are most common in this To-
cality on the cottonwoods are PeDlphigus
popuhmoniHsl Riley and Chaiopherls
~riiBriHdhs2 The former is less numerous
than the latter. The first named species
attacks the leaf near its margin. By the
continual puncturing and irritation to the
leaf the growth is retarded at that roInt.
The growth on the opposite side of the
leaf is so rapid that within a short time a
pocket like cavity is formed in which the
lice live. The other species differs in its
habits from its relative. Instead of form
ing a gall or protective covering for them
selves, they co%ngregate on both sides Of
the leaf near the mid VEN, and by their
continued puncturing SCOT cause the foli-
age to curl, become brown and finally
drop from the tree.
Nature has provided us with checks
against the ravages OF these pests. There
are numerous small 'four-wInged flies
that deposit their eggs in these lice, by
means of a sharp evipOsitor. 1t was
these little friends that saved the wheat
crop two years ago in the East when its
destruction was threatened by these lice.
The larvae from the eggs OF these -four
winged flies" live upon the vital organs of
their hosts, use their skin for a pupal
covering and eventually emerge ready to
continue their warfare.
The small reddish yellow and brown
lady bugs (coccmel;do) are great
checks upon the increase of these plant
lice. During n warm day these little
beetles are seen busily depositing their
eggs among the lice and upon the
trunks and branches of the trees. The
eggs hatch into a grub, which within a
short time destroy an entire colony OF
aphids.
Several species of flower flies.
(Syphido) are great aids IN DESTROYING
these lice. The larvae of these flies are
magGots, and the number of lice one of
these maggots will destroy in a day seems
almost incredible.
In addition to natures checks upon the
ravages Of insects, artificial means are
resorted to. Various remedies rave been
suggested for the destruction of plant lice,
but none seems to be more effective than
an emulsion of kerosene oil and soap.
This emul-ion is made as follows:
dissolve 10 two quarts of soft water
one-iourth pound of hard soap by heat
ing to the boiling point, then add one
pint of kerosene oil and stir vigorously
for from three to five minutes"
To the MIXTURE Just formed we then add
ten pints of water. This is the usual
strength, although the emulsion will kill
the lice il twelve pints OF water are
added. 1t is better to add the larger
amount OF water, as there is some damage
done to tho foliage when only ten pints of
water are added. Throughout the state
are numerous oil wells and springs which
might be utilized. 1t is possible that
where the crude oil is used a larger
quantity of the material would be neces-
sary. This emulsion should always be
applied with a force pump.
Another excellent remedy for plant lice
is bubach or pYrethrum. This is the
yellow insect powder sold in the shops Tor
the destruction of insects. If two table
~spoontuls of this be thoroughly stirred in
alarge pail full of water and sprayed upon
the trees, excellent results will follow the
application. Too much care cannot be
taken to make a thorough application,
otherwise it will do no good.