Q&A
Jun 07, 2022
2 minutes
What are these bumps on my tree’s leaves?
Ellyne Obermiller, IL
These mystery bumps are nipple galls. Hackberry (Celtis occidentalis) trees are often infested by a tiny insect called a psyllid. In spring, winged adults lay eggs on the undersides of leaves. They hatch and nymphs start feeding, which causes leaf tissues to grow around them. The galls are not harmful to the tree, just unsightly.
Q
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