AMERICAN AGRICULTURIST. 
ISO 
ence may be divided into four stages : first, the 
Egg ; second, the Larva, or worm state, which is 
peculiarly its eating and growing period; third, 
the Pupa, or dormant state; fourth, the Imago, 
which is the perfect or winged state. In this last 
stage only are the differences of sex discernible, 
and by the Fly or perfect insect by which the eggs 
are deposited which reproduce the brood of des¬ 
tructive worms. 
Fig. 1. 
Ths Pear Slug full grown. The leaf with its upper sur¬ 
face partly destroyed. (a) The egg deposited upon the 
upper surface of ihe leaf. 
This fly of the Pear Slug is described as a four 
winged (Hymcnopterous or wasp-like) insect of a 
glossy black color. The wings are somewhat 
convex on the upper side and slightly wrinkled, 
transparent, lefleeting the colors of the rainbow, 
the anterior pair having a smoky band across 
them. The legs are tipped with a dull yellow 
color. The body of the female measures rather 
more than a fifth of an inch in length, that of the 
male is smaller. They make their appearance 
twice during the Summer, the first time about the 
end of May or the first of June, the second ap¬ 
pearance about the latter end of July. On each 
occasion they lay their eggs and disappear in about 
three weeks. 
Fig. 2. 
The perfect insect or fly of the Pear Slug—magnified. 
The cross lines represent the natural size. 
The engraving, fig. 2, represents the perfect in¬ 
sect magnified. The cross lines show the natural 
size. This figure is taken from an English work, 
as I have not been able, personally, to verify its 
identity with our own insect. The other cuts are 
transcripts of my observations. The slug-fly de¬ 
posits its egg singly on the surface of the most 
matured leaves, covering it with a frothy, white, 
varnish-like mucilage, which surrounds it, and 
serves at once to attach it to the leaf, and to ex¬ 
clude the atmosphere. The small spot a on the 
ieaf, fig. I, represents the size and form of the 
egg which is seen as a dark center in the middle 
of a white spot. Fig. 3 represents the egg mag¬ 
nified, and the worm or young slug within the 
semi-transparent shell. Fig. 4 exhibits the egg 
also magnified after the insect has emerged. 
Fig. 3. Fig. 4. 
Fig. 3. The Egg magnified with the embryo Slug seen 
through the shell. 
Fig. 4. The Egg empty, after the Slug has escaped— 
magnified. 
It may here be noticed that Dr. Harris in his ad¬ 
mirable treatise on insects injurious to vegeta¬ 
tion, in speaking of the Pear Slug, states that 
“ their eggs are placed singly within large semi¬ 
circular incisions through the skin of the leaf, and 
generally on the lower side of it.” It is singular 
that a statement made with so much particularity 
should be entirely at variance with the facts of 
the case: The egg I have never been able to 
find on the under side of the loaf or in any in¬ 
cision on either side, but very plainly can it be 
seen by close scrutiny on any tree attacked by the 
slug, deposited upon the upper surface of the leaf 
appearing as a white speck about the size of the 
head of a pin. 
Fig- 5. Fig. 6. Fig. 7. 
Fig. 5. (a) The Slug, after shedding its skin the last 
time. ( b ) The skin left upon the leaf. 
Fig. 6 , (c) The Cocoon from which the insect has been 
prematurely removed, (d) The Slug, after having 
commenced its change to the fly state. 
Fig. 7. The Ichneumon fly, magnified ; supposed to be 
of the species Kncyrtus, taken from the egg of the Slug. 
When first hatched, the young slug is white 
and can with difficulty be discerned with the na¬ 
ked eye ; it commences immediately to puncture, 
with small holes, the surface of the leaf upon 
which it is produced. It soon acquires a cover¬ 
ing of greenish black slime, and is said by Har¬ 
ris to live as a worm twenty-six days, shedding 
its skin during that period five times. At its 
greatest size it is half an inch in length, and is 
now nearly or quite ready for its last moulting. 
Fig. 5, gives its appearance after it has shed its 
skin for the last time, with the forsaken skin ly¬ 
ing near it. It is now much changed in color, be¬ 
ing of a yellowish brown and somewhat diminish¬ 
ed in size. In a few hours it falls to the ground 
and immediately seeks to burrow into the soil. 
Descending to the depth of several inches it 
forms a cocoon with a shiny brown interior sur¬ 
face, and a rough exterior with grains of earth 
adhering. Fig. 6 shows a broken cocoon with the 
insect, now much further diminished in size, ta¬ 
ken out. This is the Pupa or dormant state. It 
remains in the earth after its first appearance six¬ 
teen days, -when it comes forth as the perfect in¬ 
sect, fig. 2. The second brood remain ir. their 
subterranean retreat until the succeding Spring. 
We will now consider the means for prevent¬ 
ing or palliating the injury resulting from the at¬ 
tacks of the Pear Slug. I would first remark that 
the slug is found in much greater abundance on 
weakly growing trees than on those of strong 
and rapid growth. This fact points to the first 
and fundamental remedy ; the securing of healthy 
trees and by the proper enrichment and 
preparation of the soil, of a thrifty and uni¬ 
form growth. I have also noticed that certain 
varieties of the pear are much more subject to 
its attack than others. The Bartlett, Duchess 
d’Angouleme, and Louise Bon de Jersey, for in¬ 
stance, have with me suffered more than the Clout 
Morceau, Vicar of Wakefield, and Beurre Die! 
Nature has provided a minute but formidable 
enemy to the slug, which serves very materially 
to check its increase. This enemy is a species ol 
Ichneumon fly which is also of the wasp family. 
Soon after the slug fly has deposited its egg on the 
leaf, the Ichneumon deposits its egg within the 
shell of the former, which developing to a minute 
grub before the time for the hatching of the slug 
worm, feeds upon the embryo slug, passing the 
whole period of its existence as a worm, and even 
undergoing the succeeding transformation through 
the pupa state, within the small space afforded by 
the egg of the slug, the natural size of which may 
be seen at a, fig. 1. 
Fig. 7 exhibits the Ichneumon fly as found in 
the egg of the Pear Slug nearly read}' to emerge 
as a perfect insect. 
Fortunately for the cultivator, the Pear Slug is 
easily destroyed during the worm state, and since 
the discovery that the egg is deposited upon the up¬ 
per side of the leaf, it can be easily reached in 
this stage of its existence. 
The application at the proper time of lime in 
a dry or powdered state while the leaves are 
wet with rain or dew, will prove effectual in de¬ 
stroying the egg before it is hatched, or the slug 
during the time of its depredations. If the 
number of trees to be treated is large, it will 
only be necessary to apply the remedy twice dur¬ 
ing the season, provided the proper stage of the 
insect’s developement is chosen. This should 
be as soon as possible after the eggs are all 
hatched, which is usually about the first of July 
with the young brood, and the first of September 
with the second brood. The lime should be very 
carefully dusted on every leaf of the tree, and 
by following up the application promptly for a 
year or two the number of insects will be very 
much diminished. If applied earlier than the 
times mentioned, some of the eggs will not have 
hatched, in which case it requires much greater 
care and a larger quantity of lime ; or if applied 
much later, many of them will have undergone 
their transformation into the pupa state, and 
therefore be beyond our reach. Many cultiva¬ 
tors have reported a want of success from the ap¬ 
plication of this remedy, merely from the want 
of that knowledge of the history of the insect 
which would enable them to choose the proper 
time for its use. I have found this remedy al¬ 
ways efficacious, and even plaster of Paris, ashes, 
or dust from the road applied to the slimy coat 
of the slug will cause it to sicken and die.—Ru¬ 
ral New-Yorker. 
Currant Bush Insects. 
To the Editor of the American Agriculturist: 
I write you in behalf of that old, familiar and 
useful fruit, the Currant. It is many years since 
I first noticed some of the leaves of the Currant 
bushes in my garden, which were then very 
fruitful and thrifty, to be covered with red spots. 
For several seasons, I paid little attention to them, 
as neither the fruit nor the shrub seemed to suf¬ 
fer. But at length, finding the appearance to be 
every year increasing, I searched for the cure, 
and found that wherever the upper surface of the 
leaf was turned red and slightly indented, the un¬ 
der surface was covered with lice. I then com¬ 
menced clipping off the affected leaves, and con¬ 
tinued to do so through the season. The next 
Spring, ho%vever, they appeared more wide-spread 
than before ; and since then I have been clipping 
and the lice increasing. Last season I became 
satisfied that this course would never cure—that 
