HOP-FLY. 
77 
evident signs of being uneasy, continually crawling about 
on tbe upper as well as tbe under side of the leaves, and 
leaving no deposit whatever. The direction of the wind 
has nothing whatever to do with their first appearance, but 
in a warm, westerly wind they will take flight most readi- 
ly, and be thus distributed. The lice, when half grown, 
change the skins; and I have often found the skins of 
very large ones stuck to the leaves, and yet showing no 
opening where the insect could have got out. I believe 
these are the prey of a little parasitic fly, whose history I 
don't know enough of at present to attempt to give it you 
here ; they have, however, other enemies ; and as these 
seem to offer the only hope of checking the increase of 
these destructive wretches, I shall give you a little account 
of them. 
You will never find a plant of any kind infested with 
the Aphis, without also observing a number of ants and 
lady-birds among them, and also a queer-looking insect, 
like a fat lizard, which is, in fact, the caterpillar of the 
lady-bird. The connexion of the ants and the Aphis is of 
the most peaceful kind that can be conceived ; their object 
is the honey-dew which the Aphis emits ; and, far from 
hurting the animal which affords them this pleasant food, 
they show it the greatest possible attention and kind- 
ness, — licking it all over with their little tongues, and 
fondling it, and patting it, and caressing it with their an- 
tennae in the kindest, prettiest way imaginable: — not so 
the lady-bird, or its lizard-like caterpillar ; these feed on 
the blights most voraciously, a single grub clearing a leaf, 
on which were forty or more, in the course of a day. The 
perfect lady -bird is a decided enemy to them, but not so 
formidable a one as the grub. The eggs of the lady-bird 
