The unseasonably cool temperatures during May have delayed the emergence of the periodical cicadas by two full weeks. While this has been depressing to entomologists and others anxiously awaiting their arrival, it probably has been insignificant to the cicadas. After all, they have waited 17 years to emerge. What's another 2 weeks?
We received our first report of cicada adult emergence on Monday, June 2, from Mt. Pleasant. The same day I received a message from Mike Irwin, a graduate student at Western Illinois University that he had found adults in Cass and Schuyler counties in Illinois.
Periodical cicada adults emerge at night. The nymphs climb out of the
ground after sunset and climb a tree trunk, post or other vertical surface.
They attach securely and start the job of shedding the "skin." The outer
shell splits along the middle of the back and the adult laboriously emerges
over the course of about an hour. The wings that were folded like an
accordion are expanded and the newly-exposed shell hardens and darkens. By
midnight the brand-new, fully-formed adults crawl upward to tree limbs and
branches to wait for day break.
There is a delay of a few days before the adults begin to sing. Of course, it is the singing by tens of thousands of male cicadas that attracts the greatest attention.
Insecticide controls are not recommended for cicadas in woodlands and landscapes. Apple orchards and nurseries located within cicada emergence areas may find it necessary to spray to protect trees from the egg-laying damage. Small or high-value ornamental trees in emergence areas can be protected by netting or cloth covers.
Otherwise, enjoy the show! These cicadas won't be back until the year 2014!
Additional sources of information on cicadas include:
- Horticulture and Home Pest Newsletter, May 9, 1997, page 66
- ISU Entomology Web page
- ISU Extension Web page
This article originally appeared in the June 6, 1997 issue, p. 87.