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April, 1890. 
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from the plant and thus produce the disease 
which has attracted our attention. 
Plant lice are small, soft-bodied insects, 
varying from one-twentieth to one-fourth of 
an inch in length, with the external covering 
comparatively thin and tender, thus render- 
ing them susceptible to the attacks of pre- 
daceous insects and parasites. The antennae 
are from three to seven jointed, the logs usu- 
ally long and slender with two jointed tarsi. 
The mouth parts consist of a jointed sheath, 
the labium, enclosing two pairs of long, 
bristle-like organs, the mandibles and max- 
illae, while over all, but shorter than the 
other parts, lies the labrum, the whole form- 
ing a hard, solid, jointed beak, which is used 
to pierce the leaves or bark, and as a tube 
through which to suck the sap. In most of 
the species the bodies are naked, but some are 
more or less covered by a cottony or downy 
substance which is secreted bv glandular or- 
gans on the abdomen and thorax. 
The larvae and pupae, like the larvae and 
pupae of all insects belonging to the order 
heiniptera, resemble the perfect insects in 
form and habits. Thus, although they fre- 
quently cast their skins, and the winged 
forms gradually acquire those organs, there 
is no dormant pupal stage as we find in most 
other insects. Their whole lives are, there- 
fore, devoted to imbibing food and reproduc- 
ing their kind. 
In the autumn, as a rule, the last brood con- 
sists of winged males and females. These 
mate, after which the males die while the 
female remain behind a few days to deposit 
the r eggs, after which they also die. As 
soon as the buds begin to swell in the spring, 
the eggs hatch and the young lice at once 
insert their beaks into the leaf or bark, and 
begin to pump up the sap. This brood con- 
sists entirely of wingless females capable of 
producing young without the intervention 
of the males. Instead of depositing eggs as 
did the fall brood, they are viviparous, i. e. 
bring forth living young. These are also 
all females, and in turn produce another 
brood of females in a similar manner. This 
process is repeated again and again during 
the summer, through six or eight genera- 
tions or until cold weather calls a halt. It 
was formerly supposed that the Fall brood 
consisted wholly of males and females, but 
investigation has shown that there are usu- 
ally a number of agamic females among 
them, thus showing a tendency to continue 
indefinitely their anomalous method of pro- 
duction. which is apparently checked by the 
approach of cold weather. Indeed by keep- 
ing them in an artificially heated atmos- 
phere, the production of young without the 
intervention of males has been kept up for 
over four years. By this method of increase 
it has been estimated that a single female 
may be the progenitor of over six thousand 
millions of young in a single season. 
It is this power of rapid increase that ren- 
ders plant lice of such economic importance, 
and makes it imperative that we deal with 
them promptly if at all. Early in the spring 
it is comparatively easy to destroy the few 
females that have succeeded in passing the 
winter, or the eggs of those species that de- 
posit upon trees, by spraying with kerosene 
emulsion; but so small are they, and so 
slight is the damage they do at this time, 
that we are apt to neglect destroying them 
until, almost before we are aware, the plants 
are completely overrun. In speaking of re me- 
dies for the hop-plant louse, Dr. Riley says, 
“The attack should be begun in the spring. 
When grubbing, the roots and young shoots 
should be examined, and any aphids that 
may be found, destroyed. As the vine- in- 
crease in size, they should be carefully ex- 
amined every few days, and when the lice 
appear they should be destroyed by hand, 
for the number will not be large and the 
method is certain. They spread very slow- 
ly at first and afford the grower ample op- 
portunity, should he desire to avail himself 
of it, for destroying them by means of wash- 
es or otherwise. As the season advances, 
they become numerous, spread all over the 
vines and are then practically be yond reach. ” 
Many other species which confine their oper- 
ations to the leaves, as do those which work 
upon the cabbage and some other garden 
vegetables, or small plants, such as flowering 
annuals, pot plants, etc., may be checked 
in the same manner by removing the leaf 
or leaves on which they commence opera- 
tions; and if this be done in time and any 
stray individuals seen on the plant destroy- 
ed, the remedy may be effectual. The ob- 
jection to rel\ ing wholly upon this method, 
is that if but a few stray individuals escape 
they will soon spread their colonies over the 
entire plant, and some more effectual means 
of destroying them will have to be adopted. 
Fortunately, their external envelope is so 
delicate and their hold on life so easily 
broken, that they are quite easily destroyed 
by the direct application of any acrid sub- 
stance to their bodies. One of the best 
remedies is to thoroughly spray the infested 
plants with a mixture of soft soap and 
kerosene, made by thoroughly mixing to- 
gether one part of kerosene, two parts of 
soft soap and twelve parts of warm water. 
On apple trees and other trees or shrubs on 
which eggs have been deposited, an appli- 
cation of the above mixture before the eggs 
have hatched will destroy nearly all of them 
if thoroughly applied. Such an application, 
it must be remembered, destroys only the 
lice or eggs that it touches, and if but a few 
here and there are left, their powers of 
rapid reproduction will enable them soon 
to establish new colonies, and the work will 
have to be repeated ; hence the necessity of 
applying the spray with great force that it 
may reach every insect. 
Other remedies that may be applied in 
the same manner are solutions of whale oil 
soap, decoctions of quassia, strong soap- 
suds, weak lye. lime water, tobacco-water, 
etc. Dusting the plants with road dust, 
lime, chloride of lime, tobacco dust or py- 
rethrum has also been recommended, but 
these are more difficult to apply thoroughly 
than are the sprays. Perhaps the most 
effective remedy, where it can be used, is 
tobacco smoke. To render it effective, 
however, the plant must be enclosed so 
that the smoke may be confined. It is, 
therefore, impracticable on a large scale, 
but is very effective in greenhouses or 
where only a few plants are to be treated. 
Prof. Forbes suggests, as a preventative meas- 
ure, that the kinds of plants attacked by 
any species should not be raised upon the 
same ground two years in succession. 
With all ihese remedies, and all our im- 
improved methods of applying them, so 
rapidly do plant lice multiply, that all our 
efforts to keep them within hounds would 
be comparatively useless were it not for the 
many allies we have in predaceous and 
parasitic insects. Speaking of these friends 
Prof. Cook says, “The present season 
(’89) has furnished a vivid illustration of 
their importance. Ten days ago the heads 
of wheat were crowded with hungry aph- 
ides or plant lice. These myriad lice, often 
five or six around a single kernel of wheat 
and two hundred on a single head, were 
sucking the sap and very vitality from the 
forming kernels. They were rapidly blight- 
ing the grain, and unless some friendly 
hand were raised against them the wheat 
crop would be utterly ruined. Even then, 
when the lice were countless in number 
and when the winged forms were spreading 
to the oat fields, the hand of deliverance 
was easily discerned in the comparatively 
few but wonderfully prolific enemies of the 
lice, which had already sounded a halt in 
the march of destruction. A week later 
and the enemies of the lice were in the 
ascendency, and to-day the lice are nearly 
exterminated, the wheat crop is rescued 
and the oat ciop saved.” 
If, then, we have such allies among in- 
sects, we should learn to recognize and pro- 
tect them and not destroy them under the 
impression that all insects are injurious. 
Chief among the predaceous insects which 
prey upon plant lice are the lady-bird bee- 
tles and larvae, and the larvae of syrphus and 
chrysopa flies. The beautiful lady-birds are 
known to all by their hemispherical shape 
and bright red or yellow color with . black 
dots, or black color with red or yellow dots. 
The larvae are dark-colored, elongated, six- 
legged insects, usually dotted with gray, 
yellow or oraDge, according to species. 
The syrphus maggots are legless and look 
like small, thickened leeches. The posterior 
end is large and thick, while the anterior 
end is sharp. They move with a slow, 
slug-like motion, and upon finding a louse 
stab it with their sharp mouth-parts, and, 
holding it up, quickly suck it bloodless. 
The chrysopa larvae may be told by their 
active movements as they rush about in 
search of lice to devour. 
The parasitic insets are mostly small spe- 
cies of four-winged flies, which lay their 
eggs on or in the body of the lice. When 
the eggs hatch, the ] arvae devour the inter- 
nal organs of their hosts, and then, in many 
cases, use the skin as a sort of cocoon in 
which to pupate. Scon the mature insects 
come forth, mate and proceed to lay their 
many eggs in the bodies of new victims. 
