Aphids: The Cows of the Insect World
No matter how troublesome certain things might be in your garden - like aphids, for instance - you only have to look at them closely to realize how beautiful they are. We have a native cotton plant in our garden-the one with the orange-colored flowers-and there's a little yellow aphid that seems to like this more than anything. It swarms over its leaves and stems in thousands, and when this happens to a plant, people say that it is covered with blight.
Since aphids suck the juices out of a plant and would end up by killing it if they were allowed to, gardeners do everything possible to get rid of them. But the other day we put a few of our yellow aphids under a microscope, and found that they are as pretty as can be.
They are like little golden globules. They have six long, delicate legs, the tiniest black eyes, and a black honey-tube on either side of their backs. Some of them have wings, too-big beautiful ones so fragile that you can see right through them. But these winged aphids are particularly villainous, for they fly to other plants, and start up new colonies far and wide.
There's a very strange thing about aphids. For the greater part of the year all of them are female. They are called stem mothers, and during their short lives they produce many baby aphids which quickly grow to full size and themselves become stem mothers.
Only coming up towards winter do a few male aphids appear. After this, the females lay eggs in some protected spot-perhaps in the cracks of bark-and these are able to live right through the colder months.
When warm weather comes again, they hatch out into young aphids, which soon become stem mothers-and you know the rest of the story.
Have you ever heard aphids called "ant cows"? That is because ants "milk" them- though, of course, they don't get actual milk from them, but honey-dew.
Ants are so fond of this delicacy that they often "raise" aphids and tend them, much the same as we raise herds of cattle. They even carry aphid eggs down into their own nurseries, and look after them together with their own eggs. When at last the baby aphids hatch out, the ants carefully carry them out and place them on the right kind of food plant. Sometimes they build a little mud shelter over them, as well-and all so that they themselves can go on enjoying their honey-dew.
If you have any aphids in your garden, there will most likely be a lot of ants amongst them. I'd suggest that you take a magnifying glass and watch them for a while. Every now and then you will see the ants stroking the aphids with their feelers. This is called "milking", because it encourages the aphids to give up their honeydew. So you see, here's this giving-and-taking arrangement again.
In lichen plants, one part gives water and the other part gives food. Many orchids also give food to the tiny fungi from which they receive water. And aphids give delicious honey-dew to the ants from which they accept protection and caresses.