TURNIP-FLY. 
ddl 
for the more speedy destruction of the enemy. | the ground even in January; but it requires the 
The beetles are seldom found in shady places, 
except during the winter season, and they can- 
not bear cold and wet, which are great protec- 
tions against their increase; it consequently 
follows that warmth and sunshine are far more 
favourable to their multiplication, and in such 
seasons they are most to be dreaded. Showery 
weather, after a long drought, and cloudy days 
with gleams of sunshine, also render them abun- 
dant, as such seasons do the greater portion of 
insects; but in a few instances they have been 
known to do much mischief even in cold wea- 
ther. That the turnip-beetle is endowed with 
an acute and powerful sense of smelling is proved 
by his flying against the wind, and deserting all 
other plants as soon as a turnip-crop appears in 
his neighbourhood. Mr. Le Keux says that in 
May 1836, when the thermometer was at 75° in 
the shade, during a south wind, great numbers 
were on the wing, and all proceeding southward ; 
and again, that eight acres, forming the summit 
of a hill in Devonshire, were sown with turnips, 
and when the young plants were just rising 
above the ground, the wind being for more than 
a week at south-east, wafting the scent to the 
north-west, they were so destroyed on this side, 
that nearly an acre was bare, whilst the south- 
east side was not touched until the plants had 
attained a size to render the attacks of the beetle 
of little consequence. From what has been 
stated, it appears that no season will secure us 
entirely against the attacks of the turnip-beetle ; 
and that no soil is considered safe from them is 
evident upon the best testimony ; it is very de- 
structive upon strong lands, and not less so on 
light ones. Neither is the period of their attack 
limited; for, as one pair of insects may produce 
five or six broods in a season, there is a constant 
succession, which renders any plan for extirpat- 
ing the beetle in any of its three early stages 
scarcely practicable. 
“ As the turnip when in rough leaf is not in 
any danger from the attacks of the beetle, it is 
evident that our first care must be to preserve 
the young plant; and this can only be done by 
the preparation of the soil, or using such speedy 
means the instant the beetles appear as will 
destroy or drive them away. The primary ob- 
ject will be to discover the best manure for that 
purpose, and a dressing that will render, if pos- 
sible, the soil obnoxious to the insect. It has 
been correctly said ‘that the manure which 
most effectually promotes the growth of the 
plant will be the best defence from the insect ; 
and that, when the growth is slowest, the dan- 
ger from the insect is most serious.’ ‘This arises 
in a great measure from the advantage that in- 
sects have over vegetation. A gleam of sun- 
shine is almost sufficient to call them into active 
life, as we have before observed, and as is evi- 
dent from the swarms of delicate gnats that may 
often be seen dancing in the air when frost is on 
accumulated rays of the sun, and a much longer 
duration of warmth, to set in action the fluids 
of plants. Whether any direct protection against 
the beetle can be expected from manure, since 
it is ascertained that it is not upon the seeds 
that the eggs are laid, now becomes a question ; 
for when the maggots escape from their burrows 
in the leaves, and enter the earth, in order to 
become chrysalides, before changing to beetles, 
the manure, I should think, seldom contains 
sufficient ammonia to destroy them,—and, if I 
mistake not, any moderate fermentation would 
rather facilitate than retard their metamor- 
phoses. Moreover, the instinct of insects is so | 
perfect, that the maggot would most assuredly 
avoid obnoxious spots, so that, if any manure 
were spread that would injure them, unless it 
formed a very uniform stratum, it would not 
insure success, although great advantages might 
be derived from its use——Burning has been 
found the best preventive against the beetle by 
some, which is readily accounted for, since it 
would destroy any chrysalides in the land; and 
as the beetles may be in abundance in the field 
when it is preparing for turnips, burning would, 
of course, be destruction to them,—and spread- 
ing the ashes afterwards over the ground will 
prove an additional security. But such a system 
does not suit sandy soils, neither can it be fol- 
lowed up regularly on any land.—Feeding off 
the turnips is strongly recommended as an anti- 
dote to the beetle, as well as from its peculiar 
advantages of manuring and preparing the Jand 
for the barley-crop and succeeding seeds. I am 
disposed to attribute the advantages derived 
from sheep-folding, as regards the beetle, to the 
perfect stamping down of the soil and herbage, 
by which all insect life is destroyed, rather than 
to any peculiar quality in sheep-manure, unless 
it be contained in their urine.—It is the opinion 
of a great many agriculturists that raw and long 
manure harbours the beetle; and if turnips be 
sown on a stubble-crop they are often completely 
destroyed. I see Mr. Webb Hall states that he 
has had to sow stubble-crops three times over ; 
and seed sown on stubble late in August has 
been taken off by the beetle in more than one 
instance. Whether this arises from the hollow 
straws affording a retreat for the beetles, or that 
the weeds had supported them or the maggots, 
so that the chrysalides were lying undisturbed 
in the land, is not easily explained —Mr. Linton 
and many others recommend drilling-in, not less 
than three or even four pounds of seed to the 
acre, and six or seven pounds broadcast; for he 
very justly observes that thick sowing causes the 
plants to grow much more rapidly when young 
than thin sowing; and by drilling in with the 
seed a peculiar compost, containing the strongest 
animal manures, the fly, he says, has never yet 
disappointed him of obtaining a good crop. I 
think it probable that the ammonia in this po- 
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