What plants will cicadas put at risk?

Spring is always a busy time at the Morton Arboretum. Add in millions of emerging cicadas and the season's to-do list gets exceptionally longer.

"We're doing a lot to prepare," said Spencer Campbell, manager of the plant clinic at Morton Arboretum in Lisle. He said workers at the arboretum were busy throughout the first weeks of May wrapping hundreds of the arboretum's youngest trees to protect them from this year's expected cicada brood.

"It's the same material used for a wedding veil or a tutu," Campbell said of the fabric used to wrap the trees.

While cicadas are harmless to mature trees, the breeding process can cause damage to smaller trees, Campbell said. Female cicadas prefer to lay their eggs in branches that are ¼ to ½ inch wide. To do so, the cicada makes a small incision in the branch and places about 20 eggs inside. Because each female cicada can lay about 600 eggs, one tree can be subjected to many small incisions.

"All those small cuts can have an impact," Campbell said.

Insecticides may kill adult cicadas but will not harm deposited egg masses, Campbell said. And because cicadas are a desirable food source for many animals and birds, insecticide use is not recommended.

Instead, wrapping the trees in tulle is the best way to protect them, Campbell said. To determine whether a tree is vulnerable, measure the trunk's diameter 4.5 feet above the ground, Campbell said. If it is 2 inches or less, consider wrapping the tree.

Along with saplings, Campbell said homeowners should consider wrapping woody plants such as hydrangeas, rose bushes and raspberry bushes. A video on the arboretum's website at shows the simple process.

Trees are vital to the entire life cycle of the cicada, Campbell said. Those tiny eggs, no bigger than a grain of rice, develop in the tree for six to 10 weeks before dropping to the ground, where they will feed on the tree's sap until they emerge fully developed many years later. Some broods of cicadas remain underground for 13 years, while others stay there for 17.

What the cicadas take while laying their eggs, they give back as fertilizer. Cicadas emerge from the ground wearing a hard shell known as an exoskeleton. Once discarded, the shells fertilize the tree, helping to ensure a healthy environment for the next emerging brood.

Campbell said the cicadas are loud and might be seen as a nuisance to humans, but to wildlife, they provide an unexpected feast. The bugs are so abundant and nutritious, Campbell said, animals that eat them produce larger, healthier litters of offspring in the year to follow.

"There absolutely are more positives than there are negatives," he said.

Homeowners who are planning to protect their trees this time around have no time to waste. With soil temperatures rising and leaves on the trees, Campbell said the great cicada invasion of 2024 is imminent.

"We're getting close," Campbell said.

- by Sandy Illian Bosch

Author Bio

Sandy Illian Bosch is a contributing writer to The Hinsdalean