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