The city of Ann Arbor, along with large parts of the Midwest and eastern United States, will experience a 17-year cicada emergence in May and June of 2021. The cicadas, which do not bite and are harmless to humans, will present challenges to saplings and young trees while benefiting larger and established trees. In response, the City of Ann Arbor is suspending its spring tree planting efforts and has established a website, www.a2gov.org/cicada, to help the community understand and prepare for the event.
17-year cicadas are also called periodical cicadas, which is a group that includes 13-year cicadas. Cicada nymphs live underground for 17 years and emerge near the end of their life cycle. At this point:
- The cicadas shed their skins, live for several weeks and mate.
- Female cicadas lay eggs in small tree branches and trunks.
- Adult cicadas die, new cicadas hatch and burrow into the ground for another 17 years.
- Cicadas “singing” can be heard up to a ½ mile away.
This batch only emerges when soil is 64 degrees at about 8 inches of depth, which in Ann Arbor, occurs in May or early June. Visit www.a2gov.org/cicada to learn more about the emergence and how to protect valuable trees, shrubs and other plants.