Why are some of these staghorn sumac leaves turning fiery hues before the rest of the plant?
These bright-colored leaves are home to the pouch-like galls of sumac gall aphids. While lots of these galls can cause early changing colors and shedding of some leaves, the overall impact is thought to be insignificant to the sumac’s health.
Inside of the gall is a hollow chamber crawling with tiny aphids and their frass (poop).
In spring, female aphids lay an egg on the underside of a sumac leaflet midvein, which causes the sumac to form a gall around the egg. Through the summer that single aphid hatching from the egg produces hundreds of aphid clones parthenogenically (without males). These clones are born pregnant, ready to give birth to more clones in a couple of days. In fall, the galls split open to release winged females that fly to nearby patches of moss. Asexual reproduction continues here and subsequent generations survive the winter. The clonal colonies eventually produce males to mate with the females and in spring the mated females fly to sumacs to continue the cycle.