Cicadas map shows where broods emerge as sightings start to appear in parts of US

Trillions of periodical cicadas are expected to emerge across the U.S. this spring and summer in an insect event which has not happened in over 200 years.

For the first time since 1803, two different broods of cicada will emerge across more than a dozen states, mating and laying millions more eggs, starting in May.

The giant insects hibernate as groups in either 13 or 17-year cycles.

While the cicadas are harmless to humans and animals, their loud screaming noise and vast numbers often attract the ire of locals for the month or two that they are active, including in South Carolina where the sounds caused enough concern for Newberry County Sheriff's Office to release a statement on social media.

Find out where else the broods, which can create sounds as loud as jet engines, are going to emerge by looking at the map below.

Infesting 16 states, the two broods emerging in 2024 are Brood XIX, also known as the Great Southern Brood, and Brood XIII, referred to as the Northern Illinois Brood.

Brood XIX last appeared in 2011 and is set to be unleashed in parts of Alabama, Arkansas, Georgia, Illinois, Indiana, Kentucky, Louisiana, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee and Virginia.

The other group, Brood XIII, has a 17-year cycle and last emerged in 2007.

It is set to reappear in Illinois, Indiana, Iowa and Wisconsin.

Each brood actually consists of various species of cicada - three in the Northern Illinois Brood and four in the Great Southern Brood.

Though we should be fine, a professor at Tennessee Tech University warned the infestation will likely see hundreds, if not thousands, of trees 'damaged beyond recovery'. 

Cicadas do not carry disease, but create slits in tree branches to lay their eggs. 

Consequently, experts have predicted that forested areas, including urban green areas, will see a larger infestation than agriculture regions.

Dr Gene Kritsky, a professor, entomologist and cicada expert at Mount St. Joseph University, told DailyMail.com: 'The dual emergence is a one in two or three lifetime event.

'This happens 12 times every 221 years, but this is the first time since 1803 that these broods will emerge together.' 

Already beginning in mid-to-late April, cicadas crawl out from underground when the soil reaches a temperature of 64 degrees Fahrenheit at a depth of 12 to 18 inches. 

Soil temperatures act as a signal to cicadas, letting them know the outside world is optimal for survival - but cold is not a cicada killer.

'We need two or three days above 80 degrees for the soil to reach 64 degrees,' Kritsky said.

'Cicadas have receptors that are triggered when temperatures are getting warmer.'

He continued to explain that it will take around a further two weeks for all the adult insects to emerge and the public will experience the infestation for roughly six weeks.

Kritsky added that the insects act as natural gardeners for matured trees by carving holes in branches the size of human fingers.

'That provides natural aeration in the summer and allows rain to seep into the soil and trees,' he explained.

'However, a new sapling will get killed. When females lay eggs in sapling branches, the insects sometimes that weakens that branch.

'The branch will hang there and the leaves will turn brown in what is called flagging.

'I’ve seen a young planting of an Oak tree. Cicadas were all over the branches and every branch was flagging. The tree starved to death.'

Cicadas prefer specific trees like Oak, Maple and some fruit ones like cherry and pear, with keen gardeners advised to wrap any young trees' branches in a mesh netting if they want to keep the insects at bay. 

The insects are also drawn to younger trees because of the diameter.

People who have recently planted trees can wrap the branches in a mesh netting to keep the cicadas at bay.

‘Generally, mature trees can sustain minor damage from cicadas,’ according to Davey, a professional tree service company based in Ohio.

‘Young trees, however, can experience canopy loss and a reduction in photosynthesis due to their limited number of branches.’

There are more than 3,000 known species of cicadas.

The cicadas form 15 major 'broods' of cicadas in different geographic areas.

These insects emerge from the ground in droves, with some years seeing trillions of cicadas in a season.

One thing which makes these creatures so interesting is the ability to harden their exoskeletons, which takes about five days, and shed it in order to being flying.

Kritsky said cicadas can create an unpleasant odor.

'As soon as they start coming out of the ground, people are screaming, 'They’re going to kill my trees,' and then the wonder what that smell is.'

The odor happens as the insects are dying and the decaying process sets in.

The loud signing is done only by males as a way to attract a mate.

After its mating call captures a female, the pair mate and the female lays eggs in the tree.

The nymphs then drop out and burrow underground to begin their own hibernation- and the cycle starts again.