How Do I Protect My Plants From Cicadas?
What Are Periodical Cicadas?
You may be thinking that you see or hear these cicadas every summer, but those are likely different species of annual cicadas. Periodical cicadas (Magicicada) hibernate underground and emerge only once every 13 or 17 years. They’re grouped together into “broods” based on the year they are expected to emerge. Recently hatched cicadas almost immediately burrow underground and spend these years hibernating before returning in swarms. Once the soil temperatures are above 64°, they will crawl out of their burrows, leaving holes behind. They’ll spend 4-6 weeks traveling, laying eggs, and feasting on plants.
Remember when you thought you wouldn’t use math again? Well here is a prime example of math in nature! Both 13 and 17 years are prime numbers, which you may think is a coincidence at first. But, it’s not! They are synchronized to come out in full force to ensure some of the population survives getting eaten by predators. This phenomenon is called “predator satiation”.
So why prime numbers? Predators and prey have population cycles depending on food availability and competition, and this cycle will shift so predators will have a high population when their prey does. By emerging every 13 or 17 years, predators can’t easily sync their population cycle with cicadas, because they are prime numbers!
What Does This Mean For Your Garden?
These periodical cicadas are sometimes mistakenly called “17-year locusts”. Don’t worry! They are not locusts and are not arriving as a Biblical plague to destroy your garden. After emerging, they like to crawl up mature trees to shed their skin, and then will travel to other trees and shrubs to eat and lay eggs. They don’t even have teeth, so how much damage can they do?
Cicadas are mostly beneficial! They prune mature trees, aerate the soil, feed wildlife, and once they die, their bodies serve as an important source of nitrogen for plants.
Mature plants don’t suffer much damage, even if they’re covered in swaths of cicadas. However, young shrubs and trees may benefit from a little protection. You can cover your plants with mosquito nets, light curtains, or other fabrics for protection. Do NOT spray pesticides on your plants! It won’t successfully wipe out cicadas from your garden, and will just poison birds, possums, and other predators that feed on the cicadas.
Check out this map from the US Forest Service to see if your garden will be impacted by cicadas:
Are They Safe For Humans?
Yes, they’re completely safe! We’ve heard some rumors that people think they’ll lay their eggs under the skin of small children, but that is completely a myth. They lay their eggs on slender stems of trees and shrubs. You can rest easy hearing the songs of the cicadas without worrying about your safety.
Did you know that some people even eat these cicadas? You can even find recipes for cooked dishes online! Definitely not suggesting it, but maybe I shouldn’t knock till I try it. Perhaps after the next 17-year cycle.