affecting Carrots and Paisnips. 
195 
stigma is smoky-green : the legs are ochreous, sometimes tinged 
with green; the hinder thighs are reddish-brown at their extre- 
mities ; all the shanks are black at their tips, and the feet are of 
the same colour : length f line ; expanse 3 lines. 
This Apliis resorts to the parsnips the beginning of June, but I 
have never known any fatal effects from its inroads, as amongst 
the carrot crops. The Aphides, however, which last summer 
smothered such a great variety of fruit-trees, shrubs, vegetables, 
and flowers, were congregated in countless myriads on the under- 
side of the parsnip leaves, and there they died packed close 
together with their heads down and their wings a little elevated 
over their backs. 
A Summary of the present Essay. 
Parsnips perhaps the best substitute for the potato. 
Carrots subject to the attacks of a variety of insects. 
The carrot-leaf plant-louse hilling one-tenth of the crops about 
Midsummer. 
Powdered tobacco dusted over the carrots, or watering them 
with a decoction of tobacco, will kill t-lie aphides. 
Another species of aphis infests the roots in the autumn. 
The Rust is occasioned by the maggots o/" a fly called Psila 
rosce. 
These maggots infest the carrots in summer and winter, boring 
labyrinths round and through the tap-root. 
They change to pupce in the earth, and the flies are hatched in 
the spring. 
Slugs and Podurce also inhabit the unsound roots. 
The maggots of Psila nigricornis are, probably, equally in- 
jurious. 
Sometimes they attack the carrots when very young. 
Remove the infested roots as soon as the leaves turn yellow, and 
burn them. 
Trenching the ground in the autumn, one of the best securities 
against most insects. 
A dressing of spirits of tar and sand before soiving has been 
successfully tried. 
Pigeons^ and coic-rfwra^ pointed -in at the time of sowing, will 
secure the crop. 
Quick-lime sowed and ploughed-in will free the soil from 
maggots. 
Millipedes and centipedes also infest the injured carrots. 
The Otter caterpillar of the ghost-moth will devour carrots as 
well as hop-roots. 
Draining is circumscribing the localities of many insects. 
o 2 
