ROSE LOUSE. 
335 
ter this insect secures itself under the bark of trees 
or elsewhere. When the warmth of spring has 
expanded the foliage of plants, the female deposits 
its eggs on them in great numbers, from whence 
in a short, time proceeds the larva, a small grub 
of a dark lead colour spotted with orange: these 
may be observed in the summer season running 
pretty briskly over all kinds of plants ; and if nar- 
rowly watched they will be found to devour the 
aphides wherever they find them. The same may 
be observed of the lady-bird in its perfect state. 
As these insects in both their states are very nu- 
merous, they contribute powerfully to diminish the 
number of aphides. Mr. Curtis mentions another 
very formidable enemy : it is a very minute black 
and slender ichneumon fly, which eats its way out 
of the aphis, leaving the inflated skin of the insect 
adhering to the leaf like a small pearl. In General 
the torpid aphis submits quietly to this fatal opera- 
tion ; but this is not the case with all of them, as 
Mr. Curtis observed the kind which feeds on the 
sycamore, which has more agility than many of the 
other species, endeavouring to avoid the ichneumon 
with great address. 
Mr. Curtis is of opinion that these insects are one 
of the principal causes of the blight of plants, and 
supposes that they emigrate to different parts of the 
country at certain periods. He informs us that the 
common green aphis, which is so generally de- 
structive, lives during the winter season on such 
herbaceous plants as it remained on during the 
