Returning to central Missouri after a brief visit to Florida, we found twigs and clumps of leaves scattered across the lawn; also noticing numerous broken stems in the canopy of some trees (especially the maples and mimosas), we initially assumed that a powerful wind storm had passed through Columbia. On closer inspection, however, we saw grooves on the underside of these terminal branches, indicating that cicadas had produced the damage.
Though their adult life is limited to a week or two, female cicadas can cause significant damage to young trees and shrubs by carving a linear trough along terminal stems in which to lay their eggs. Since tender shoots are favored, young trees are more severely affected and, in some cases, the numerous wounds are fatal. The massive number of periodical cicadas is especially devastating to regional vegetation while the annual cicadas, just now emerging, produce limited damage.
We often ponder how each plant and animal species plays a unique role in nature's delicate balance but uncovering the importance of periodical cicadas, which spend 13 or 17 years beneath the soil followed by 2 weeks of frenzied mating and tree damage, is a challenge indeed. Their mass emergence may play a role in soil aeration, their huge numbers provide a welcome bounty for many birds and mammals and their glut of rotting bodies may be a valuable source of nutrients for growing plants; however, the associated damage to trees makes one wonder if these benefits outweigh their cost to the ecosystem. Then again, cicadas, like all other species, are focused on the survival of their genes, not on the welfare of their natural environment. They may not realize it and we may not like it but, so far, they have been very successful at evading extinction.
