Stories from the NFCCA Newsletter, the “Northwood News”

Northwood News ♦ April 2021

Nurturing Nature

The Cicadas are Coming!

By Jennifer McGuire Cox

Brood X, that once-in-a-17-year group of cicadas that stoke fear in some and excitement and intrigue in others, is coming to our area this May and June.  Be prepared by learning more about what they are, their lifecycle, and what you need to do to prepare!

What are Cicadas?

Cicadas are insects that are probably best known for the loud calls made by most male cicadas in the summer months.  These sounds, which are used to attract females for mating, are made by vibrating membranes found on their sides, beneath their wings.  These calls are said to be so loud that they rival the sounds of some jet engines.  They’re also quite large by most insect standards, with a body length of roughly an inch and a wingspan of three inches.  While cicadas are found worldwide, periodical cicadas — those that emerge en masse — only occur in North America.

Different Cicadas:  Dog Day vs. Periodical

There are two types of cicadas in our area: the “dog day” or annual cicadas that we hear every summer, and the periodical cicadas, or Brood X, that only emerge every 17 years.  Both types start out in the ground and spend years as nymphs (young/immature insects), sucking on nutrients from plant roots for energy.

The Periodical Cicada

The length of how long they stay underground is one big difference between the two.  For “dog day” cicadas, they stay underground for two to eight years, and have a staggered emergence so they appear to us annually.  The periodical cicadas usually stay underground for 17 years and emerge all at once.

The timing of their emergence and appearance are different as well.  Dog day adults appear later, late July through mid-August, while periodical cicadas emerge mid-May through June.  Dog day cicadas are also greenish in color, whereas periodicals have red eyes and orange wing venation [veins].

The Lifecycle of a Periodical Cicada

Periodical cicada nymphs begin to burrow tunnels toward the surface when soil temperatures reach 64 degrees F.  When they break through to the top, the cicadas will climb to the nearest vertical surface, such as a tree or fence, and begin their metamorphosis.  Their old outer skin, also known as an exoskeleton, is shed, and what emerges from its remains is an adult cicada with newly formed wings.  The cicadas stay on this vertical surface for some time, allowing gravity to aid them as fluid is pumped into their wings and their skin hardens.

Once this process is complete, cicadas will usually spend their brief adult lives, only about six weeks in total, in trees looking for a mate.  The males will sing, females will respond, and mating begins.  Females will then deposit their eggs in thin tree branches, the eggs will hatch six to ten weeks later, termite-looking young emerge, and then these young fall to the ground, burrowing into the soil and starting the process all over again.

Why Every 17 Years?

Why do our local periodical cicadas come out all at once anyway, and why every 17 years?  This commonly timed emergence, or synchrony, is a survival strategy.  Cicadas don’t have any real natural defenses.  They don’t have stingers to defend themselves with, they’re not toxic, and they don’t even move fast.  By emerging all at once, they overwhelm predators.  Sure, some will be eaten, but their sheer numbers are just too many for predators to eat.  This ensures that a large number survive.  It also guarantees a greater selection of mates.

Sometimes, however, not every cicada gets this message and some might appear in an off-year.  These stragglers can emerge four years early or four years late from the rest of their brood.  It is believed that it was accelerations of growth by these stragglers that eventually caused new broods of cicadas to develop over time.  Currently, 15 broods are active in the eastern and central United States, all in cycles of 13 or 17 years.  Having a prime number of 13 or 17 is less likely to result in cicada broods overlapping with each other and to reduce the likelihood of further synchrony.

Are They Harmless to Plants?

While cicadas can’t sting or bite you, they can do damage to small trees and shrubs due to their egg laying habits, especially those planted in the last few years.  Female cicadas use a long, thin appendage at the tip of their abdomen, called an ovipositor, to gouge a series of holes into the twig-like branches of trees.  In these holes, the females will lay their eggs.  While they might occasionally feed on the fluid found in these young twigs, they do not bother the leaves and otherwise leave the plant alone.

While mature trees are able to sustain such damage, young trees and saplings, whose crown consists mostly of these thin branches, often cannot, and either will have their growth stunted or they could possibly die.  As a result, experts recommend that those with trees on their properties planted in the last two to three years consider covering them during the cicada emergence with a 3/8" wide mesh netting.  This is small enough to prevent cicadas from getting into the crown of the tree to lay their eggs but large enough to allow other beneficial insects and pollinators access.  Tulle can also be used as another in case mesh netting cannot be found.

Using cheesecloth and mosquito netting to cover trees is not recommended and spraying trees with pesticides is not as effective and can also kill other beneficial insects.  Likewise, wrapping sticky, flytrap-like material around the trunk of your tree is also ineffective as cicadas can fly and avoid it altogether.

Cicadas favor native trees and shrubs; those especially vulnerable include maple, oak, hickory, apple, cherry, ash, hawthorn, black locust, birch, dogwood, redbud, and nut trees.  If you’re planning on planting new trees or shrubs, it’s recommended that you wait until the fall of 2021 to ensue their survival.

Can You or Your Pets Eat Cicadas?

Cicadas are generally edible for humans and pets and are a good source of protein.  There are numerous recipes and cookbooks available with ideas on how to cook up cicadas.  Those who have eaten them say that they taste like asparagus, popcorn, or shrimp.  If, however, you have a shellfish allergy, you should not eat them as cicadas are distantly related to shrimp and lobster and are actually nicknamed “the shrimp of the land.”

Cats and dogs can have fun eating them as well, although veterinarians suggest limiting your pets to only two or three at a time as they consider them fatty and worry too many can make your pets sick or lead to problems such as pancreatitis.  There is also a risk that pets can choke on their rigid wings and body parts.  Before you and your pets scoop up any cicada off the ground though, make sure that there isn’t a chance that it could have been sprayed with pesticides or other chemicals.

More Information on Cicadas

Cicada Recipes
Feeling adventurous?  Try out some recipes in the “Cicada-licious:  Cooking and Enjoying Periodical Cicadas” cookbook put together by Jenna Jadin and the University of Maryland Cicadamaniacs in 2004.  It is available for download here.
Citizen Science Opportunity
Interested in helping scientists document the periodical cicadas?  Then download the app “Cicada Safari.”  Just take a photo of a cicada and upload it to the app!  The app is free and available for download for Apple and Android devices.

[Jennifer McGuire Cox is a naturalist at Brookside Nature Center and Maydale Conservation Park.  She is also a certified Maryland Master Naturalist; she lives on Belton Road.]   ■

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