TURNIP-FLY. 
they differ from one another chiefly in the colour 
of the legs, and in the form of the longitudinal 
yellow stripe on the wing-cases. It is very un- 
likely that they are more than varieties of the 
same species ; and however important it may be, 
in most other instances, to discriminate closely 
allied kinds of insects, this is of little conse- 
quence in the present instance, as all those men- 
tioned, whether varieties or species, are alike 
prejudicial to the turnip, and are doubtless pre- 
cisely similar in both their methods of mischief, 
and the modes in which they may be kept down 
or destroyed. 
The Haltica nemorum, as well as each of the 
allied kinds, occasionally feeds on a variety of 
cruciferous plants; but, as already intimated, it 
is more particularly attached to the turnip, 
which it attacks both in its perfect and larva 
state. When the plants have acquired some de- 
gree of strength, and the foliage is considerably 
developed, the injury done is usually insignifi- 
cant, as the partial consumption of the leaves 
does not interfere so materially with their func- 
tions, as to have the effect of diminishing the 
size of the bulb. In this respect the larva of the 
turnip saw-fly, Athalia spinarum, is incomparably 
more to be dreaded, as its greater size and vo- 
racity demand a much larger supply of material. 
But unfortunately the favourite food of the flea- 
beetle is the young plant, just as it is beginning 
to unfold the cotyledon leaves. These it con- 
sumes with the utmost avidity; and when it is 
abundant, it often, in a very short time, strips a 
whole field of its crop. It has, for so small a 
creature, a truly astonishing voracity; and has 
been observed, when shut up for the special exa- 
mination of its habits, to consume no fewer than 
ten plants every day. The loss which it some- 
times occasions, in years and districts favourable 
to its prolificity, is enormous; and so long ago as 
1786, Mr. Young stated that the turnip-crop de- 
stroyed by it in Devonshire alone was valued at 
£100,000. | 
“The economy of this little pest,’ says Mr. 
Curtis, in a long and able paper, of which we 
shall here give an abstract, “has puzzled the 
man of science, as well as the practical agricul- 
turist, for many years; and for want of that 
rigid care which is indispensable in the investi- 
gation of natural history, numerous errors have 
been adopted, which have led to the promulga- 
tion of many false theories. Dr. Pearson believed 
at first that the white spots or dots observable 
on more than half the turnip-seeds were the eggs 
of the turnip-fly ; but he was compelled to aban- 
don that opinion, having had no flies where the 
seed was sown in soil contained in pots covered 
with bell-glasses. Rusticus, however, a contri- 
butor to the Entomological Magazine, so strongly 
insisted upon it, that seeds steeped in brine, or 
otherwise prepared, have been sold in London at 
the seed-shops, to insure the grower against the 
attacks of the fly. It is exceedingly likely that 
IV. 
O29 
the white dots are occasioned by minute flies 
alighting upon the seeds while they are drying, 
and depositing their excrement upon them, which 
is often white; or they may be particles of pollen 
from the flowers. It was, however, from the 
careful investigations of Mr. H. Le Keux that 
we were first made acquainted with the actual 
economy of this little beetle. If the spring be 
warm the sexes pair from April to September, 
during which period the eggs are deposited by 
the female on the underside of the rough leaves 
of the turnips. She lays apparently about one 
egg daily; and ten pairs laid in a week only 
forty-three eggs. This indeed was under con- 
finement; but the correctness of this estimate is 
supported by the fact, that in leaves taken from 
the field, containing as many as six larve, they 
were all of different sizes, indicating a variety of 
ages. The eggs are hatched in ten days; and 
the little maggots immediately begin to eat 
through the lower skin of the leaf, and to form 
winding burrows by feeding on the pulp. These 
burrows are visible enough to the naked eye 
when the larve leave them, and the cuticles are 
withered and discoloured; but in their early 
stage, they are discovered with difficulty; in- 
deed it is only by holding the leaf up to the 
light that they can be well detected. The larvee 
are full fed in about sixteen days, when they 
desert their burrows and bury themselves not 
quite two inches below the surface of the earth, 
selecting a spot near to the bulb, where the tur- 
nip-leaves protect them from wet and drought. 
In the earth they become immoveable chrysa- 
lides, which are brought to maturity, I believe, 
in about a fortnight, when the beetle, or fly, as 
it is called, emerges from its tomb, again to fulfil 
the laws of nature. The beetles themselves are 
rather long-lived, for they have been kept in that 
state from July until the following February. 
Highteen inches is about the greatest extent of 
their leap, which in a straight line, would be, 
averaging their stature, 216 times their own 
length; and when it is remembered that this 
leap is performed in a curved line, it must be 
admitted that a considerably greater distance is 
achieved. They seldom walk, and when at rest 
sit with their hind legs folded under them, ready 
to skip off in an instant, if disturbed, or when 
even approached. In warm weather, during 
sunshine, with the thermometer standing be- 
tween 70° and 80° in the shade, they fly with 
facility. 
“This little plague is not confined to our 
island, for it is abundant in Germany, and com- 
mon everywhere in Sweden, where it is very 
destructive in its perfect state. Probably in 
England no portion of the country is perfectly 
free from these insects; at least every bank and 
meadow harbours them to a greater or less ex- 
tent; and they have been found also on grass- 
Jands which had not been ploughed for many 
years, and where there were no turnips within 
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