2o 4 LIFE AND HER CHILDREN. 
lay the eggs to be hatched next year. But if you 
look in the early spring you will find no winged 
plant-lice or aphides, but only the little round-bodied 
green forms, and yet new ones are constantly appear- 
ing ! Where do these come from ? 
Do you remember how the hydra of the jelly-fish 
went on budding and budding for years before another 
true egg-bearing jelly-fish appeared ? (see p. 64). Now 
we have an insect doing the same thing, for as soon 
as one of these wingless aphides is about ten or twelve 
days old, there come from her body not eggs, but 
young living aphides like herself, three, four, or even 
seven a day, which struggle over the backs of their 
companions till they find a clear spot on the stem, 
where they fix their mouths and suck like the others, 
only moving to struggle out of their skins about 
three or four times a day, till they are full grown. 
Then these young ones begin to bud in the same 
way in their turn, so that in a very short time from 
two or three mothers a whole plant is covered. In 
fact it has been reckoned that a single aphis 
may give rise in one summer to a quintillion 
(1,000,000,000,000,000,000,000,000,000,000) of 
little ones ! 
After this we shall not be surprised that the 
plant-lice have taken possession of so many of the 
green things in the world, and the only wonder is 
that they have not destroyed them all. This they 
would certainly have done if it were not for their 
enemies ; but the birds delight in them as dainty 
morsels, beetles and earwigs devour them, and flies 
lay eggs in their bodies, while the lady-bird eats no 
other food ; and the blind grub of a fly (Musca 
