INSECTS INJURIOUS TO THE TURNIP CROPS. 
9 
Of far greater benefit to the agriculturist than either the lady- 
bird, or the larvae of the Syrphidae and lace-winged flies, is a 
minute hymenopterous insect, about 1 J lines long and 2 lines 
in expanse of wing. Towards the middle of October, the 
turnip-fields swarmed with this useful insect; your clothes 
would be quite covered with them ; of course, they were not 
distinguished by an ordinary observer from the aphis — this was 
the Ichneumon ci'pliidum of Linnaeus, the Ajpliidius (Trionyx) rappee 
of Curtis. I dare say some of my readers have noticed on the 
under sides of the leaves of almost any plant affected by the 
aphis, some dry, puffed-out skins, generally of a light brown 
colour. These bodies are evidently those of an aphis; you 
see his legs, head, and the anal tubes ; there can be no mistake 
about his aphis character ; he is, however, quite motionless. By 
a careful inspection of these occupants of your leaf, you will 
notice in some cases a small round hole opening out from the 
back of the bodies (see fig. 6). Out of this bach door the little 
parasite has emerged. The Apliidius belongs to the Ichneu - 
monidce , and the female had deposited, after the manner of that 
family of insects, an egg in the soft body of the Ajphis, which 
turning into a maggot lived on the vitals of the plant-louse, 
changed into a nympha, and then into the perfect insect. About 
the end of October, the farmers' hopes brightened; the cold and 
rain had annihilated the “ smother-fly," and the turnips, though 
small, showed signs of vitality, by putting forth from the crown 
a few fresh green leaves. The crops would grow now, it was 
supposed, and though the bulbs would not attain to any size, 
it was at least expected that they would be sound. But, alas ! 
as formidable an enemy as either grub or smother-fly was 
stealthily doing his work of destruction underground. We 
take a turnip up, the upper part seems externally sound 
enough; the soil which attaches itself to the root prevents 
our seeing the injury I am next going to notice. Let us 
brush the soil away — and now we see brown erosions and 
portions of the tap root quite rotten ; let us slice away, 
and we find a whitish maggot, about four lines long, with a 
pointed head, out of which he protrudes a curious organ 
furnished with two black hooks (by means of which he scrapes 
tunnels in the bulb), and a truncated tail end, having in the 
centre two projecting brown spiracles, from which proceed 
along the back a pair of silvery trachese ; the truncated end 
is surrounded with about a dozen serratures. Hardly a turnip 
is free from some of these maggots ; most of the turnips con- 
tain numbers ; some, — and these have not put forth any fresh 
leaves, — are completely riddled through and through, and 
quite rotten ; the decomposition has been evidently caused by 
the maggots (see fig. 7 a and b). If we examine the soil 
