Happy Mystery Monday! Can you guess what is pictured in photo #1?
The answer to last week’s mystery is a wool sower gall pictured in photo #2.
The wool sower gall is caused by Callirhytis seminator, a tiny cynipid gall wasp in the family Cynipidae. These strange, woolly growths appear on oak twigs in Spring after the wasp lays her eggs, triggering the tree to form a protective nursery around the developing larvae.
Inside the fuzzy gall are small, hard, seed-like chambers where the grub-like larvae feed and grow. Gall wasps use chemical compounds to stimulate these highly specific plant growths, and each species creates its own unique gall. Though they may look alarming, wool sower galls typically do not cause significant harm to healthy oak trees.
The adult wasps are incredibly small, only about 2–5 millimeters long, and are seldom seen. They overwinter as larvae inside the gall, then pupate in the gall or soil before emerging in spring. Once adults chew their way out, they live only a few days, long enough to mate and lay eggs. The galls themselves may ooze a sugary sap that attracts ants, butterflies, and bees, and after the wasps leave, empty galls can become shelter for scavenger insects, spiders, and other tiny opportunists. Gall wasps do not bite or sting humans and pose no threat to our health or safety.
Mystery Monday is sponsored by the Spy Newspapers and Adkins Arboretum.
