Widespread damage due to periodical cicada outbreak
While the periodical cicada outbreak known as Brood II has finally wound down, the after effects of all that mating and egg laying have not gone unnoticed as widespread damage to oaks and other trees are now visible in areas across the Commonwealth, according to officials at the Virginia Department of Forestry.
“After mating, periodical cicada females lay eggs in the thin-barked outer branches of many different trees and shrubs by slicing into the plant tissue with a sharp organ called an ovipositor, which is also used to lay eggs,” said Dr. Chris Asaro, VDOF forest health specialist. “Within each sliced area, known as an egg nest, they deposit up to 20 eggs.”
Asaro said that a single female can create about 30 egg nests, laying as many as 600 eggs.
“When you consider how many millions of female cicadas were laying eggs over the past few weeks, there are literally billions of slices in the trees,” he said. “ All of these cuts along the length of the outer branches can cause enough structural damage to kill the terminal, which turns brown, a phenomenon known as ‘flagging’ or ‘twig dieback’.”
In areas with very heavy cicada emergence, heavy flagging may be apparent, particularly on oaks and trees overhanging fields and roads. This flagging is now visible to varying degrees across much of Virginia’s Piedmont and Coastal Plain. The degree of flagging on any individual tree may vary from a few scattered branches to almost every available twig. While this may be a major concern to many, most medium- to large-sized trees will not suffer any serious long-term damage.