Demery Coppola of Guilford, Connecticut, found this leaf on the Saint Michael’s College campus in Vermont during her Environmental Science lab. Do you know what’s on its underside?
Answer
Hackberry nipple galls, which are growing on the undersides of leaves. Adult hackberry gall psyllids (Pachypsylla celtidismamma) are 1/10-inch long insects that lay eggs on hackberry leaves as they break bud in spring. The leaves respond to chemicals released by the hatchling larvae to grow galls in which the insects live and feed until they emerge as adults in fall. Thanks to Declan McCabe for passing along the photo and information.
This week’s contest winner was Larry Clarfeld