Tuesday, June 26, 2007

Dog Day Cicadas

After several weeks of hot, humid weather, the annual cicadas are beginning to emerge in central Missouri. Unlike their periodic cousins, which appear in huge numbers during late spring, this species waits for the stifling conditions of mid summer and is thus called the Dog Day Cicada. And while their periodic counterparts remain underground for 13 or 17 years, the larvae of the annual cicadas are ready to emerge within two years; populations mature each year and, in contrast to the explosive arrival of periodic broods, their emergence is spread over 8 to 10 weeks.

Upon reaching the surface, the larva climbs onto a tree, fence or building to dry out and molt to the adult form. Its adult life, lasting but a week or two, is dedicated solely to breeding; the males attract mates with their high-pitched "song" (which tends to peak in the evenings) and the females lay their eggs on the tender vegetation of shrubs and trees. Though they don't eat during their brief life span, adult cicadas are prized snacks for crows, starlings, blue jays, raccoons and house cats.

Cicada eggs may remain on the plants through the winter, providing nourishment for chickadees, titmice, nuthatches and yellow-rumped warblers, or may hatch and drop to the ground. Once on terra firma, the larva burrows beneath the soil, attaches to the root of a shrub or tree and patiently waits for its 2-year confinement to end.