Now, let us go in search of the aphids, or aphides, as they are also
called. We shall not have to search far.
[Illustration]
In a very dry season we generally need not search at all. All we need do
is to examine the nearest weed to find plenty of aphides.
Yes, they are the little plant lice that seem at times to cover every
growing thing.
Sometimes they are green, sometimes brown, or gray, or reddish, in
color.
They are tiny creatures, but what they lack in size they more than make
up in numbers.
Go now, and find some aphides.
Ah, here you all come, each bearing a leaf or a twig on which are
aphids.
There was no trouble in finding them!
They do not hop like the jumping plant lice when they are disturbed.
They remain where they are unless they are very much shaken up.
See, most of them are without wings, though here are a few with
beautiful transparent wings.
Antennæ they have, long and threadlike. And see, the knowing little
eyes!
They seem to be anchored to the leaf.
Hold the leaf up to the light, and see if you can discover what they are
doing.
Ah, see those mouth tubes firmly stuck into the leaf. There they stand
all day long and suck out the juice.
[Illustration]
Ned says he should think they would burst.
But they do not; they grow. And they also get rid of a large part of the
superfluous sap in a curious way.
They use what they need to grow on, and the rest escapes from the
insect's body in the form of "honey dew." It is a sweet liquid of which
ants and bees are very fond.
What, John, you have heard that the aphids give out honey dew from two
little horns near the tip of the abdomen?
Let us see if we can find these horns. Yes, we can see them plainly, and
_very_ plainly with a magnifying glass.
But now listen; the honey dew does not come from the horns. On the end
of some of the horns, or tubes, we can see a drop of clear liquid.
For a long time people believed this was honey dew, but instead, it is a
waxy substance which is not sweet.
It has been very carefully studied by wise men who tell us it contains
no sugar and is probably used as a means of defence, as aphides have
been seen to smear the faces of insect enemies with this wax.
There are a great many species of aphides, and not all of them have the
little tubes or horns on their backs. But probably many that have no
horns give forth honey dew.
It is really a waste substance from the body of the aphid.
Ants are so fond of the honey dew that certain species of aphides have
been called the _ants' cows_, because the ants take care of them for the
sake of the honey dew.
Some ants protect the aphids from their enemies. They drive off those
insects that would devour the aphids, and when winter comes these ants
carry the aphids down into their warm nests under ground, and keep them
safe through the cold weather.
The aphides cannot stand wet weather, but after a long spell of dry
weather they will be found in great abundance.
[Illustration]
Sometimes they eat so fast and so much that the honey dew falls like a
shower from the trees upon which they are. It covers the ground beneath
and the leaves of plants, and makes everything very sticky and
disagreeable to the touch. The dust settles on it, too and a growth
something like mould often turns it black--as we find to our discomfort.
But when the honey dew is fresh the bees love it. They collect large
quantities of it and make it into honey. Squirrels like it to.
It is great fun to watch the nimble squirrel folk sitting in the trees
and holding a leaf between their little hands while they lick off the
honey dew.
Children sometimes suck the honey dew from the leaves in back country
places, where sugar is scarce and where candy is seldom to be had.
Which side of the leaf does the aphid prefer?
Yes, it is on the under side always.