Until recently, I’ve often collected these round tan globes found on the ground underneath the Valley Oak tree(Quercus lobata)… until I found out exactly how they are formed. These lightweight, bulbous lumps are called ‘galls’ which are tumor-like growths created when the female oak gall wasp injects her eggs into the oak tree tissue. Once laid, the eggs secrete plant hormone replicas to create a protective shell-like chamber or gall which starts off green in color until ripened. The larvae mature inside the gall and bore a tiny exit hole when ready to depart. You can see a tiny hole there in the largest tan gall. The larvae may remain in the gall for weeks or months, and even years. Yikes, the gall!