124 Insects. 



sown earlier, had grown too large to be so easily destroyed : 2ndly, 

 On account of the property of the leaves to retain water longer than 

 those of any other turnip. Thousands of these little insects might be 

 observed sitting on the under side of every leaf, which they did not 

 eaty but extracted the moisture from it in such a manner, that at the 

 end of three or four days the turnip was completely killed, and could 

 be crumbled between the finger and thumb, like scorched leaves. Be- 

 tween five and six hundred acres of turnips were totally destroyed in 

 this way in the neighbourhood of Alnwick and Wooler, particularly 

 about Millfield-plain and Flodden-field, though in the southern parts 

 of the county, and on the Scotch side of the Tweed, there were none 

 to be seen, or at least so few as not to be noticed. They were also 

 sometimes found on the wheat and oats, and in one instance a quan- 

 tity of wheat was entirely spoiled from having been bound up into 

 sheaves with a great number of Aphides upon it. On the sheaves be- 

 ing opened again after two or three days, they appeared as if glued 

 together, and had a very offensive smell, and the wheat was of course 

 entirely useless. The Aphides were never found upon ripe oats, but 

 were more numerous on the unripe than on any other kind of corn. 



Various kinds of insects used to feed on these Aphides : — the red 

 and black ants, Ichneumon flies, the larva of the large red lady-bird, 

 and the caterpillar of a fly whose name I do not know. These cater- 

 pillars used to seize the Aphides and suck their juices from them : 

 this was a very curious operation ; when the insect had seized his 

 prey, he raised his head in the air, and continued in that position un- 

 til there was nothing left but the skin of the Aphis, which it got rid of 

 by (as it were) wiping its mouth on the turnip-leaf In this manner 

 it would eat from fifteen to twenty at a time, and then remain inactive 

 for half an hour, and then again feed, one caterpillar would thus de- 

 stroy about a hundred in a day. The colour of the caterpillar was a 

 transparent green, barred towards the tail with reddish brown and yel- 

 low, in length about half an inch. The chrysalis was reddish brown, 

 always fixed on the underside of a turnip -leaf. The fly was about 

 half an inch long, head large, and, together with the thorax, reddish 

 brown ; the wings as long as the body, rounded and transparent : the 

 body darker brown approaching to black, ban*ed with bright yellow 

 like a wasp. The caterpillar was about ten days old before it became 

 a chrysalis, and remained in that state other ten : the flies lived only 

 three or four days, but were very quick and active, continually hover- 

 ing over the turnips in great numbers, and appearing to settle on them 

 very seldom, and then only for an instant. 1 kept a great number of 



