By David Wall
Starting in June and carrying on into July every year, we all get to listen to what’s usually and erroneously referred to as the 17-year cicada. Actually, there are seven periodical cicadas. To the east and north, there are three 17-year and four 13-year cicadas, leaving us in the NETSEO area with any of the other 150 species.
Cicadas in our area are called annual cicadas. No, they don’t finish their life cycle in one year, but some emerge in a non-synchronous manner every year. It still takes several years for their life cycle to occur, and the exact number of years varies.
Life cycle begins when cicada eggs are deposited in small tree twigs. Six weeks later, tiny cicada nymphs hatch, fall to the ground, burrow into the soil and begin sucking on root xylem, which is taking nutrients to the tree above ground. The xylem, nutritional wise, is only slightly better than water, hence the years required to become fully grown.
At maturity, nymphs emerge for a final molting, crawling up a tree or shrub. If, however, there are no trees or shrubs, they’ll just molt on the ground. Adults have many predators, but their sheer numbers ensure adults survive to lay eggs.
Cicadas communicate with tymbals; a set of ridges of each side of their abdomen. Muscles contract & release these tymbals 300-400 times per second, creating a buzz which is amplified by an echo chamber. Males buzz to attract a mate. Receptive females respond by snapping their wings, and so the life cycle continues.
Be very glad we don’t have either the 17 or 13-year cicadas, as their numbers and buzzing sounds are enormous. A Single mature tree may have as many as 20-30,000 cicada nymphs on their roots, which apparently don’t really harm the tree.