The Cicadas are here!
The other day when I was walking on the sanctuary property, I saw my first cicada exoskeleton of the year. This year is special in particular for cicadas because an enormous brood is emerging from living underground for 13 years. It’s the nation's largest brood of periodical cicadas. Their range covers parts of 16 middle and eastern states, including most of Missouri and Illinois.
When 13-year cicadas hatch from their eggs, they are but 1/10th of an inch long. These “nymphs” crawl down to the earth, bury themselves 10 inches underground and attach to roots, growing as they extract nutrients. When they emerge after thirteen years they shed their larval exoskeleton (see photo below) to turn into an adult, growing wings and building up strength to fly and find a mate. During this period forest creatures will have a feast; but there are billions, many more than predators can eat.
In order to attract a mate male cicadas will produce loud clicking noises by flexing drum-like membranes on their abdomens called tymbals. Multiply that single noise by the swarms of males in a single neighborhood, and you hear a high-pitched buzzing sound that never seems to cease. Males can spend up to six weeks trying to attract females. The month of June will be a noisy one!
When I saw this cicada exoskeleton sitting on a leaf I thought to myself, “What effect will billions of these insects in the trees have on the forests?” There are greater numbers of cicadas in areas with abundant trees, and it's estimated that as many as 1.5 million of them could emerge in a single acre. Females tear gashes in small, woody branches of trees and shrubs and lay hundreds of eggs inside. Very young trees with trunks less than an inch in diameter could suffer the most. Young trees can be protected by covering with fine netting. However, to have any chance of being effective, the net must completely cover the tree from the ground up. Most trees, though, suffer no ill effects from any cicada species.
Tree growth decreases the year before the appearance of a brood because of the increased feeding on roots by nymphs. Moles, which feed on nymphs, do well during the year before an emergence, but decrease the following year because of the reduced food source. Wild turkey populations benefit from eating dead cicada adults on the ground, as do other ground feeding birds and mammals. Uneaten carcasses decompose on the forest floor and create a rush of nutrients for the forest ecosystem.
Cicadas aren’t dangerous to people or pets, they don’t bite or sting and humans should try to enjoy this unusual spectacle of nature!
Submitted by Sara Oliver, World Bird Sanctuary Naturalist
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