Will the Cicadas Eat Your Plants?

It’s easy to wince thinking about the mass emergence of insects like cicadas. Their numbers can reach millions per acre, creating a near-deafening buzzing chorus. So it’s understandable that questions like, “Will Cicadas eat my plants?” imediately spring to mind. But cicadas are also pretty fascinating and play important roles in the ecosystem.

“Cicadas inspire wonder in our world!” says Jennifer Hopwood, Senior Pollinator Conservation Specialist at the Xerces Society for Invertebrate Conservation. “They spend most of their life underground next to the same plant roots. Somehow, these creatures are able to track the years that pass by and time their emergence with other periodical cicadas in the region to overwhelm predators. They are amazing little critters.”

Here’s a rundown of what to know about cicadas, good and bad, including whether or not they eat plants and how to protect your trees during an emergence.

What Is a Cicada?

Cicadas are insects with broad bodies and wingspans up to three-and-a-half inches. “They are known for their prominent eyes set wide apart, transparent, veined wings and the males’ distinctive, loud song,” says Shartrina White, Vice President of Education at Butterfly Pavilion.

Cicadas belong to a group of insects known as true bugs, in the order Hemiptera. Others in that order include aphids, planthoppers and assassin bugs, all of which use piercing and sucking mouthparts to feed from plants.

When Do Cicadas Come Out?

It depends on the species. The most famous ones are periodic cicadas that surface every 13 and 17 years, typically between April and June. But other cicadas appear every summer, between July and September.

“Soil temperature can affect emergence,” says Daniel A. Herms, Vice President of Research and Development at The Davey Tree Expert Company. “Adult cicadas are triggered to emerge when the soil temperature at about eight inches deep reaches approximately 64F.”

What Do Cicadas Eat?

Nymphs, which are the immature, underground stage of cicadas, feed on fluids from tree roots. Adult cicadas will eat plants sometimes, too, sucking sap from young trees, tender twigs and deciduous shrubs.

Are Cicadas a Threat to Your Garden and Landscape Plants?

Possibly. Cicadas create holes in small branches and twigs, in which they lay their eggs. This can harm young deciduous trees, plus create cosmetic damage.

“It can kill the small twigs and leaves at the end of branches, causing flagging [breaking] of foliage in the canopy,” says Herms. “Tufts of dead foliage may appear alarming, but this light pruning of a relatively small number of twigs has minimal impact on healthy, mature plants.”

However, cicadas typically leave mature trees and most herbaceous plants alone, including garden plants and fruit. They also do not lay eggs in shrubs, grasses or wildflowers, nor do the nymphs feeding underground pose a threat to plant health.

How to Protect Trees from Cicadas

Before an emergence, cover small and newly planted trees with fine mesh netting or cheesecloth. Make sure to secure it around the trunk, to keep cicadas from climbing up into the branches.

“Say no to insecticides, as they can make matters worse by getting rid of the cicadas’ natural predators,” says Marc Mayer, TruGreen‘s Director of Technical Operations. “If you see cicadas setting up camp on your plants, spray water from a garden hose on them to deter the critters from eating your plants.”

Also, keep outdoor pools covered to prevent cicadas from damaging the pool filter, and avoid planting new trees the year before a major emergence is expected.

“Once egg-laying is complete, usually within a few weeks, prune away branches that appear significantly damaged to encourage new growth,” says Herms. “Also, remember that the benefits cicadas provide outweigh the potential for harm.”

What Good Do Cicadas Do?

A lot. “Cicadas are food for many species of animals, including birds, chipmunks, foxes, raccoons, squirrels, mice and other insects like the cicada killer wasp, a gorgeous, large wasp that carry cicadas into their underground nest to provide for their young,” says Hopwood.

Cicada nymphs and adults also help aerate soil, improving water infiltration and root growth. “Cicadas leave exit holes in the ground after emerging, which can provide the same benefits as aeration by creating an easier path for nutrients and water to enter the soil,” says Mayer. Then, as they decompose, they also add vital nutrients to the soil.

Cicadas are also a great educational opportunity. “My kids enjoy picking them up off of tree trunks and setting them on their fingers to watch,” says Hopwood. “Kids also enjoy looking out for the shells they leave behind on trees, the exoskeleton they shed when they transition from nymphs to the winged adults that we are most familiar with.”

FAQs

How long do cicadas live?

Cicadas spend most of their lives underground, as nymphs, which means two to five years for annual species and up to 17 years for periodical ones. Once they emerge, adults live two to six weeks, during which time they lay eggs in trees.

“After six to 10 weeks, cicada nymphs emerge from the eggs and immediately fall to the ground,” says White. “They then burrow underground and attach themselves to tree roots. Their emergence serves as a reminder of the natural cycle and resilience.”

Can cicadas bite?

No, cicadas cannot bite humans. “Cicadas have piercing and sucking mouthparts; they don’t have the ability to bite,” says Herms.

Are cicadas harmful?

No, cicadas are not harmful to humans. “Cicadas do not bite or sting and are harmless to handle,” says Hopwood. “Their legs do have little velcro-like projections that help them attach to trees, and these can tickle a bit.”

Are cicadas and locusts the same?

No. Cicadas are part of the order Hemiptera, while locusts are grasshoppers in the order Orthoptera. They differ in anatomy, behavior and lifecycle. “Locusts refers to certain species of grasshoppers that form swarms, large groups that fly around to find vegetation to consume,” says Hopwood. Locusts are generally more destructive to plants, and are especially damaging to crops, whereas cicadas are not generally considered a major plant pest.

About the Experts

Shartrina White is Vice President of Education at the Butterfly Pavilion in Westminster, Colorado, where she uses her nearly 25 years of experience to steer a dynamic team of educators, interpreters and volunteers toward curriculum and outreach initiatives. Butterfly Pavilion is the first standalone non-profit insect zoo in the United States.

Jennifer Hopwood is Senior Pollinator Conservation Specialist at the Xerces Society for Invertebrate Conservation where she builds training programs for beneficial insect management and landscape restoration. She is also co-author of several books, including Farming with Native Beneficial Insects and Farming with Soil Life.

Daniel A. Herms is Vice President of Research and Development at The Davey Tree Expert Company. He has a Ph.D. in entomology and was a professor of forest and shade tree entomology for 21 years in the Department of Entomology at The Ohio State University.

Marc Mayer has more than 28 years of experience in the horticulture and lawn care industry and currently serves as TruGreen‘s Director of Technical Operations.

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