Treehoppers under sunflower leaves, gardener bitten by carpenter ant

Q: A couple of weeks ago, I was out weeding under the tall sunflowers we had planted. Something bit me, and I realized it was a huge black ant on the sunflower leaf. It wasn’t a sting, it was literally a bite. When I looked up, I realized the undersides of many of the sunflower leaves had masses of large black ants. They seemed to be congregating, not just wandering aimlessly. Any idea what they were doing?

A: Ah ha!

When I looked at your photos on my computer screen I saw that indeed there were other insects besides the ants present under the leaves. You have a population of keeled treehoppers, Entylia carinata, insects that suck sap from the leaves and secrete sweet honeydew, which ants love.

The carpenter ants are “farming” the treehoppers. If your sunflower leaf dies, they will move the treehoppers to other leaves. They were defending their herd when you were bitten.

Curing the problem is simple: blast the treehoppers and ants off the leaves with a water hose.

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