17-year cicadas

When will Lancaster County see another swarm of cicadas?

Pennsylvania managed to leave 2020 behind without a murder hornet-sighting.

This year’s upcoming insect invasion shouldn’t come as a surprise. We’ve had a 17-year warning.

Millions of cicadas will emerge this spring and shed their skins before finding a mate. They’ll be hard to miss as a chorus of singing males tries to attract females.

These cicadas are part of Brood X, the Great Eastern Brood that covers the largest geographic region, from Georgia to New York, according to Cicada Mania. That includes Pennsylvania.

Here are more cicada facts to explore from Penn State Extension and University of Connecticut. Both websites have a wealth of information to explore. You can also see a map of sightings and report your own on the Cicada Safari app.


Where do cicadas live?

The periodical cicada (Magicicada)is the longest-living insect in North America. While annual cicadas are found all over the world, periodic cicadas are only found in the eastern half of the U.S.


Are we getting a plague of locusts?

Cicadas are often called 17-year locusts, which is not correct. Colonists in the U.S. saw swarms of cicadas and thought to the locust plagues in the Bible. There are locusts but they are several species of grasshoppers, not cicadas.


Why is this a big deal in 2021?

There are annual cicadas, so every year, some cicadas emerge. The population increases when periodical cicadas show up.

Not all periodical cicadas are the same schedule. Several species have a 17-year cycle and several have a 13-year cycle. Each species has several broods with Roman numeral names. The biggest one, geographically, is Brood X, which emerges this year.


What’s the cicada’s life cycle?

The cicadas in Brood X have spent 17 years underground. In April, nymphs burrow up to about an inch below the soil and wait. When it’s time to emerge, they crawl up trees, weeds or anything upright and leave their nymphal skins behind. This is called ecdysis. Cicadas in a brood sometimes emerge on the same night or over several nights.

After mating, females lay eggs in twigs and branches of trees and woody shrubs. After emerging, cicadas live for about four to six weeks. The nymphs hatch in six or seven weeks, drop to the ground and dig down to find a spot for the next 17 years. 


When will the cicadas emerge in Lancaster County?

Gene Kritsky, a cicada expert and dean of the school of Behavioral and Natural Sciences at Mount St. Joseph University in Ohio, shared a formula with Cicada Mania. That predicts cicadas will show up in Lancaster County on May 19.

In a few clicks, you can find the date for other areas.


Why do they make so much noise?

Blame the male cicadas, who sing to find a mate. Females are silent.

Some of the louder choruses of insects can reach 90 decibels when measuring under the tree. That’s about the same level as a shouted conversation.

The songs vary between the species. Remember the scene in Star Wars where C3PO and R2-D2 are walking through the desert? The sound in the background is cicadas. They also show up in a Marvel movie.

After emerging, cicadas live for about four to six weeks so the noise won’t last all summer.

Cicadas are daytime singers and also have short bursts of sound on rare hot nights. Night insect noises are probably crickets, katydids or frogs.

Get schooled on invasive plants before they return this spring

Will they hurt me?

No. Cicadas are not toxic or poisonous. They don’t bite or sting defensively.


Will they hurt my plants?

Cicadas don’t eat leaves but they can damage twigs during egg-laying. Twigs slit for cicada eggs often will have leaves that wilt and die. Those damaged twigs can break off. While cicadas may feed on plants and trees, they probably won’t hurt most plants.

Young trees are at most risk for potential damage. Young trees can be covered with a mesh cloth to prevent egg-laying. (Netting with a mesh no larger than ¼ inch (.5 cm) will control injury on branches, according to Virginia Cooperative Extension. Keep netting tied well enough to prevent mammals and birds from being trapped. Remove netting around July 1.)Or wait to plant new trees until next year. However, wait to see how many cicadas are in your neighborhood. You have a week before females start laying eggs and might not need to do any extra work.

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