Cicadas on the way: How McHenry County is prepping for the mass arrival and where you can track sightings

A mass of cicadas are on their way, and anyone with young trees planted in the last few years in McHenry County may want to cover them with sheer fabric before the periodic cicadas start emerging.

The bugs, which have been underground feeding on tree roots for the last 17 years, will begin emerging once soil temperatures reach about 64 degrees at 8 inches of depth, said John Fiorina, interpretive services director for the Crystal Lake Park District. Before the bugs die off, the females will lay their eggs on thin branches.

Cicadas don’t really eat plants, said Brenda Dahlfors, master naturalist program coordinator for the University of Illinois Extension’s McHenry office.

“They don’t bite and they don’t sting,” she added. “The only damage they could cause is on newly planted trees. The females like to lay eggs in branches the size of a pencil.”

Park district and McHenry County Conservation District officials are preparing for the emergence of the 17-year Northern Illinois Brood, but are not planning to tent their young trees. The Morton Arboretum in west suburban Lisle, however, started tenting young trees the week of April 29 to ensure the tender branches are not destroyed by the bugs, which cut into the limbs to lay their eggs.

Cicadas are making a lot of noise in the media because two periodical cicadas – the 17-year and the 13-year broods – are both expected in Illinois this year. It is the first time they’ve emerged at the same time since 1803 – when Thomas Jefferson was president, Aaron Burr was vice president and the Louisiana Purchase doubled the country’s size.

McHenry County is expected to see the 13-year brood; those are regulated to counties farther south.

Traditionally, the 17-year cicadas start emerging in mid-May, Fiorina said, but it could be earlier this year with the warmer temperatures.

“With the weather like it has been ... we have already had a day pushing 80 degrees in April,” which could bring the cicadas out earlier than expected, he said.

Parkland and conservation district properties are ripe for cicadas because the trees and land there has not been disturbed, Fiorina said.

“If you are in a subdivision that was not in existence 17 years ago, you are not going to be in an area with cicadas,” Fiorina said. “The trees were not there for the nymphs to hatch.”

Trees planted in those subdivisions over 17 years ago might also survive the cicadas’ arrival without damage, too, because the bugs are just not there, Fiorina said.

“My understanding is they don’t fly miles and miles away. It is a slow creep. You have got to be near a forest preserve, a conservation district or a park” with trees for cicadas to expand out from, he said.

On older, more mature trees, there may be thousands of pencil-thick branches for cicadas to lay eggs. After the eggs hatch, those branches may snap, giving the tree a bit of a trim but not causing permanent damage.

“It is nature’s pruning,” Dahlfors said.

For younger trees, Dahlfors said, that pruning can cause significant damage, which is why newly planted trees should be netted to prevent the cicadas from laying their eggs there.

What cicadas will do a few days after they emerge from the ground is sing. The male cicada’s call “is the loudest of the insect world and the deafening chorus of the whole population making noise at once is said to deter and distract predators who cannot pinpoint from where the noise is coming,” said Kim Compton, the conservation district’s visitor services coordinator.

An individual male cicada’s call can reach 100 decibels – somewhere in the chainsaw or gas-powered lawn mower range. The 17-year brood is expected to hatch millions of bugs.

The conservation district is also asking its park users for help tracking the periodic cicadas, said Caitlynn Martinez-McWhorter, the district marketing manager.

“We’re asking visitors to snap photos of their cicada sightings both in our conservation areas and elsewhere around the county and to submit them” at MCCD.me/CicadaData, Martinez-McWhorter said. A map that displays submitted entries is at MCCD.me/CicadaMap.

“Not only do we hope for this to be a fun and interactive way to educate the public about cicadas, but it will also help us identify the best locations to plan cicada-related programming in another 17 years,” she said.

The conservation district is not planning to tent its trees, however.

“While netting is recommended for a landowner looking to ensure limited damage occurs on individual trees, the district manages for communities. Our planting timing occurs when trees have the greatest chance of maximizing root development. When root development occurs, the trees are better able to handle damage,” Conservation Ecology Manager Gabriel Powers said.