78 AGRICULTURAL REPORT. 
The pear slug, Selandria cerasi, a brownish-green, slimy slug, feeding 
Fig. 34. upon the leaves of the pear tree, deposits its eggs singly 
in June, in incisions made by the piercer of the female 
under the skin of the leaf. The larvae, batching, eat the 
substance of the ieaf, leaving the veins and under skin 
untouched. The pupa is formed in oblong oval cavities 
under ground. The insect appears in about fifteen days 
after the slug has gone into the ground, in June and 
August, and lays its eggs for the second crop, which go 
into the ground in September and October, and remain 
until the following spring, when the perfect fies come out to lay their 
eges on the foliage Mr. Saunders, of Canada, states that this insect is 
readily destroyed by dusting the tree with air-slacked lime. Coal-oil 
will injure the trees, and road dust is of little value when dusted over the 
trees. For another insect of the same genus, Harris recommends syring- 
ing with strong soap-suds. The rose slug and other injurious slug 
worms can be destroyed by dusting the plants with the powdered 
hellebore, or syringing with a strong decoction of the same root. 
The perfect insect of the potter wasp, Lumenes fraterna, is beneficial, 
Fig. 35. as it stores its singularly formed mud-nest with liy- 
ing but apparently paralyzed caterpillars as food for 
its larve. A single nest taken this season was found 
to contain sixteen to eighteen caterpillars, and all 
of them a species feeding on the willow. In Massa- 
chusetts it is said to stere its nest with caterpillars of 
the canker worm. The larve of the wasp itself is 
subject to parasites, a8 a species of two-winged fly 
(Toxophora?) was raised from the vase-like clay nest of - 
a potter wasp found in Maryland. 
A bnttertly has lately made its appearance in the 
neighborhood of New York and Long Island which is 
new to the gardens there, the caterpillar of which has 
already done very great damage. This insect is the 
common cabbage-butterfly of KEurope, Pieris rapa, (Linn.,) called by 
the Canadians vér & ceur, or heart-worm, from the habit it has of not 
only eating the outside leaves, but of destroying the heart of the eab- 
bage. It was probably introduced into Quebec in 1856 or 1857 from 
Europe, in the ege state, on the under side of cabbage leaves thrown out 
from some vessel, and in 1864 it had not extended more than forty miles 
from Quebee as a center, but in. 1866 it bad found its way into New 
Hampshire and Vermont, and in 1869 was said to have been found in 
Hudson Oity and Hoboken, and no doubt the coming year it will spread 
into Pennsylvania. The females de- 
Big. 36. posit their eggs on the cabbage. 
The caterpillars are of a green color 
with black dots, having a yellowish 
stripe down the back and a row of 
z= yellow spots on each side, and feed 
$ upon the leaves and bore holes in 
the solid head of the cabbage, ren- 
dering it filthy and unfit for use. 
The pup are suspended by a web 
of silk at the end of the body, into 
which the hooks of the tail are 
twisted, and by a thread of silk 
around the back, which is fastened 
