The Gardener's Corner
The dog days of Cicada
by Judith Rogers

Every year as we reach the end of July and slide into the hot, dog days of August you can hear the unmistakable loud buzzing of the male cicada. He makes the loudest sound of all insects as he vibrates the ribbed plates in the two drum-like sound chambers called timbals in his abdomen.

There are many types of cicadas and most can be found every year because they have unsynchronized development. The periodical cicada are synchronized and depending on the species, will all mature and emerge at the same time after spending thirteen or seventeen years underground.

The female has a blade-like ovipositor on her abdomen which she uses to create tiny slits in bark to lay twenty to thirty eggs in each opening and will make many on several branches to accommodate the four hundred to six hundred eggs laid in her life time of four to five weeks. The eggs mature in six to eight weeks and the tiny ant-like nymphs drop from the trees to burrow in the ground 5 - 46 cm deep in search of tree roots to feed on.

It is known that the temperature in the ground is one factor that causes the nymphs to begin tunneling to the surface where they will climb trees and poles to molt. They are able to shed their brown brittle exoskeleton when it splits open at the back and they can wiggle out. The nymphs are vulnerable during the molting process of evolving into the large fly-like adult; it takes time and the wings have to dry before they can fly off into the tree tops to begin the mating calls so familiar to us on a hot day.

Cicadas do not bite or harm humans and animals, many nymphs become food for birds and their tunnels aerate the soil. The females during egg laying can cause some small branches to fall off trees but in effect it acts as a measure of pruning and stimulates future growth.

I'd like to thank my fellow Master Gardener Paul Smith who was kind enough to share his pictures of this molting nymph at the South Innisfil Arboretum on July 9 with me when my camera battery had run low.

In the first picture you can see the split exoskeleton with the cicada beginning to emerge; in the second it is completely molted and the wings are starting to unfurl; the third shows the adult hardening and the wings drying.