Periodical cicadas can cause tree “flagging”, which occurs when the females deposit eggs in small grooves they make in branches. If enough females choose the same branch, the branch will turn brown and die. For most adult, healthy trees, the cicadas actually can benefit your garden, because they choose the weakest branches of the trees to lay their eggs, acting as natural “pruners”. But for newly planted saplings, vulnerable trees, and prized trees & shrubs that are especially worth protecting, periodical cicadas could cause irreversible damage.
