Neighborhood Nature

Our Family's Nature Blog

Bumps on Hackberry Leaves? They’re Nipple Galls June 18, 2009

Filed under: Animals,Bugs,Plants,Seasons,Summer,Trees — saltthesandbox @ 5:53 pm
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Hackberry trees grow in many places in our neighborhood: Planted in city parks and along streets, growing wild in alleys and along rivers and streams. You can recognize Hackberries year round by their warty looking bark, and in summer by their leaves:

Hackberry leaves have teeth and taper towards the tip -- and they are often covered with bumps, called Nipple Galls.

Hackberry leaves have teeth and taper towards the tip. They are often covered with bumps called Nipple Galls.

Up close the galls really do look like baby-bottle nipples — that have fallen to the ground and been covered with tiny hairs:

Up close, the bumps look like hairy nipples.

Up close, the bumps look like hairy nipples.

Galls are odd, greenish shapes that grow on plants. Many galls form when insects lay their eggs on leaves or stems. The gall becomes a nursery for the baby bugs, which feed on the insides  — the gall is shelter and food at the same time.

So, we decided to take home some Nipple Galls and cut them open to see what was inside. Here’s what we found:

We cut open the Nipple Galls and found green stringy stuff, but no bugs big enough to see.

We cut open the Nipple Galls and found soft, green, foamy, stringy stuff -- but no bugs big enough to see.

So, maybe there were bug eggs in there, but there were no bugs big enough to see (without a microscope). Time to search the web, and here is what we found. The insects that cause Nipple  Galls look like tiny cicadas and are called Psyllids (SILL-lids). You can read more about Psyllids and Nipple Galls here and here and here.

So, now we have something else to look forward to this summer. We were already looking forward to finding real Cicadas (perhaps by the end of June). And we were looking forward to finding Hackberry fruits (that taste a bit sugary and are eaten by birds like Robins and Crows). Now we can look forward to cutting open Hackberry Nipple Galls in a month or so and finding the young — and maybe the winged adults — of tiny bugs that look like Cicadas.

And we really like Cicadas — so much that we made a website all about them, called Kids’ Cicada Hunt.


Update added October 21, 2009: On October 20th we cut open some more Nipple Galls. Go here to see what we found:  We Found Tiny Insects Inside Hackberry Nipple Galls


Here are some links to information about plant galls:


3 Responses to “Bumps on Hackberry Leaves? They’re Nipple Galls”

  1. OK, I now know that those hideous bumps on my hackberry leaves bear the equally lovely name of “nipple galls” and are caused by jumping plant lice. Great. My tree service calls these things harmless. Well, two years ago, my neighbor’s tree had such a bad infestation that all the leaves fell off. Aside from cutting down my seventeen-year old hackberry, is there no way to get rid of these things? This is supposed to be an ornamental shade tree. Some years it is neither. On the other hand, I do want to be environmentally sound and not kill off the insect kingdom of my yard. What to do?

  2. Phil Says:

    I have the same problem. My tree is only a couple of years old and looks half-dead because of these bugs. All the leaves are full of holes and/or nipples. I am about to cut it down since I’ve found no remedy for the problem short of going chemical on the entire block. I’ll just find a tree that’s less susceptible to the winged bastards.

  3. MKnoll Says:

    Just read your post after seeing bumps on my hackberry- we have lived her 11 years and I have never noticed them before! wanted to let you know that our Hackberry tree is on our boulevard in Oakpark- but not your Oakpark- we are in Oakville, Ontario, Canada!

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