What’s In My Backyard?

Backyard Safari: Ant Farmers

For the introduction to this series, see here

Did you know that somewhere in your yard there might be a group of heavily armed shepherds guarding a vulnerable flock of livestock from huge predators? It is true! The shepherds are ants, the sheep are aphids and the predators are aphid eaters, lacewings, and ladybugs. The ants protect the aphid swarms on plants driving away ladybugs and other predators. The aphids are soft-bodied and have no natural ways to defend themselves. In return for their guard service, the ants “milk” their six-legged sheep. When an ant is thirsty, it approaches an aphid sheep and rubs its back. The aphid squeezes out a drop of a substance called honeydew. This liquid is very high in sugar and makes an ideal food for ants. The aphid shepherds also remove the bodies of aphids from the plant when they die. This may help prevent the spread of disease. In some cases, the ants even carry the aphids to new plants when the old plant is used up.

This is the ideal time of year to find aphids. Look on plants in your garden for aphids and ants. When you find them watch carefully with a magnifying glass and you may see the ants milk the aphids or chase away predators. I have several plants in my yard where I can watch this amazing insect relationship. The last time I visited them, I saw the ants chase away a ladybug “wolf” that was attempting to steal some of their “sheep”!