Have you found yourself picking up broken tree branch tips from your lawn recently, only to find your lawn cluttered with them again the next day? What’s causing this continuing loss of leafy twigs? There are a number of possible causes. The one that is at work in most of Missouri this year is damage from the egg-laying of the periodical cicadas, which were singing to us from the tree tops last month.
You surely recall that the 13-year periodical cicadas emerged from the ground in late April or May, shed their exoskeletons or shells, dried their wings, and then flew around and made a constant racket with their singing for several weeks. The singing was part of the mating ritual of the adult cicadas. They mated, the females laid their eggs in the twigs of trees and all of the adult cicadas died. Thirteen years in the ground and then one loud reproductive orgy before dying.
The female cicadas used their ovipositors to saw narrow slits in the undersides of small, green twigs, laying several eggs in each slit. Many of the leafy twigs in your lawn will show that series of slits where the eggs were left. The physical damage from sawing into the twigs causes some of the twigs to break, especially following windy conditions such as we have with summer thunderstorms. Some of the twigs don’t break, some break but remain attached to the tree, and others break completely and fall to the ground. The effect of the dead twigs that remain on the tree is often referred to as “branch flagging.” The loss of twigs produces minimal harm to the tree, the equivalent of a very light pruning. For the cicada-slit twigs that don't die or break off, the wounds will heal and the twigs will continue to grow. Before long, the twigs that were going to break will have already done so and your cleaned lawn will stay clean.
As mentioned earlier, there can be other reasons for a loss of leafy twigs from your trees. Explore more info that shows how the twigs themselves can point you to the cause of the damage.