by Traci Willis, Outreach Specialist
Many headlines have begun to default to negative metaphors such as “invasion” or “infestation” when reporting about the upcoming periodical cicada emergence called Brood X. It’s true that at their highest concentration, there may be 1.5 million cicadas per acre in some areas. While that can feel overwhelming, cicadas aren’t harmful to people or pets, and they don’t bite or sting. In reality, they’re nearly defenseless!
What they will do is provide many benefits to the ecosystems where they emerge. They will prune weak tree branches, aerate and fertilize the soil, and provide increased food resources (both underground during the year leading up to hatching and especially the year they emerge above ground). This abundance will be relished by fish, turkeys, squirrels, voles, birds, amphibians, insects and spiders.
Raptors and larger mammals will also benefit from this bounty, because their prey will be well-fed. Even humans with an adventurous appetite can eat them as a good source of protein.
Despite often being lumped in with locusts, cicadas are not at all related to the grasshoppers that are capable of destroying fields of food crops. And Brood X cicadas aren’t the same insects as the annual “dog days” cicadas that emerge annually near the end of summer. The periodical cicadas of Brood X are smaller than their annual cousins at just 1.5 inches. They’re also black with red eyes, while annual cicadas are green.
Cicadas are best known for the songs sung by the male cicadas. Males sing by flexing their tymbals, which are drum-like organs found in their abdomens. Small muscles rapidly pull the tymbals in and out of shape. Their songs are heard from early morning into late evening if there are adults present.
Brood X cicadas begin life as a rice-shaped egg, which the female deposits in a groove she makes in the twig-sized branches of a tree limb. The groove provides shelter and exposes the tree fluids, which the young cicadas drink.
These grooves can kill small branches. When the branches die and the leaves turn brown, it is called flagging. If damage to a newly planted seedling occurs, it will likely sprout again from the root collar.
The eggs stay in the branch for six weeks, after which the nymphs emerge to drop to the earth. They will burrow down to the tree roots, where they will drink for the next 17 years without causing damage to the host tree.
This spring, in their 17th year, they will re-emerge as adults once the soil temperature reaches 64 degrees, after a warm rain.
On properties with no trees older than 17, there may not be very many cicadas present. Here’s why: The cicada nymphs need to feed constantly while underground and they can’t travel any great distance in the soil. They have spent the last 17 years drinking from the tree’s roots. If the tree wasn’t an established tree 17 years ago or it has been removed, there won’t be any cicada adults to return to the surface this year.
A final reminder: These periodical cicadas are native to our ecosystem. The trees in our forests and yards have survived many generations with the periodical cicadas. Healthy, established trees can withstand any damage by egg-laying cicadas. We only have about six weeks to enjoy this extraordinary phenomenon, so let’s sit back and marvel at this amazing show.
Interested in sharing a cicada experience with other nature-lovers? We are planning a cicada talk on Friday, June 18 at 4pm at Oliver’s Woods. Bug Expert Dr. Elizabeth Barnes from Purdue University will be joining us for the talk. Find more upcoming events on our calendar.