Saturday, July 12, 2014

First Annual Cicadas

As warm, muggy air pushed back into Missouri, I heard the first annual cicadas in our shade trees last evening.  After several years underground, where they feed from the root of a tree or shrub, the nymphs emerge by mid summer, climb a tree and molt into the adult form.

Focused solely on breeding, the adults may live for a few weeks if not consumed by a predator (jays, crows and house cats, among others).  During that time, the male attracts females with a loud, buzzy call that builds to a crescendo; these calls, often delivered in unison and especially prominent on mid-late summer evenings, may be heard into September.  Females dig a shallow groove in the tender, terminal limb of a tree or shrub and deposit their eggs within those tracks; this practice often kills the limb and clumps of dead leaves soon speckle the summer woodlands.

Once they hatch, newborn nymphs drop to the ground and burrow into the soil, not to emerge for several years.  Their entry and emergence burrows aerate the soil and the nymphs themselves are potential prey for mice, shrews and moles.  How vital cicadas are to woodland ecosystems is a subject for debate but their prolific breeding, so evident on summer evenings, has ensured their survival in nature's realm.