Wednesday, September 19, 2012

Hackberry galls

Pachypsylla sp.
Sometimes, we find the most unusual and strange things in our Wildscape. The other day, James spotted this hackberry leaf on the ground and showed it to me. Hmmm. Verrryyyyy interesting! I'd never seen anything like it before.The tiny protrusions looked like miniature flowers. I took some photos and emailed them to daughter Lindsey, who's taking at botany course at Angelo State University this fall. She shared them with her professor, who observed that "the leaf growth is altered by feeding of insects or mites. These look like leaves with blister galls from feeding by psyllid larvae."

The leaf's top side
So I checked and found similar photos....looks like we have hackberry blister gall psyllids (Pachypsylla celtidisvesicula), also called jumping plant lice. According to Texas A&M AgriLife Extension's online field guide, hackberry gall psyllids are not considered to be pests and will not harm the tree.

"Common leaf gall forming species overwinter in the adult stage in bark cracks and crevices," states the AgriLife field guide. "Adults mate in the spring and females lay eggs on the underside of expanding leaves. Nymphs hatch from eggs in about 10 days and begin feeding, which causes leaf tissue to expand rapidly into a pouch or gall around the insect. They develop through several stages before emerging as adults in the fall (September), although the hackberry bud gall maker overwinters inside the gall as a last stage (5th instar) nymph to emerge as adults in early summer. One generation occurs annually."

Just a while ago, I fetched a second leaf. Then I took a small knife and opened a blister. Inside was a teeny-tiny white larva. Next, I broke open a "flower." Inside was another tiny larva but butter yellow in color. How in the world do they get out of the leaf?

"Nymphs mature and then exit the gall once leaves have fallen," states a Ohio State University Extension fact sheet. "They cut a slit in the gall to permit emergence. Thirty minutes later, nymphs molt to adults. Several thousand adults may emerge from a single hackberry tree in late-September, reaching their peak in October."

By the way, adults resemble tiny cicadas, which also molt in a similar process. All verryyyyyy interesting!

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