Robert Brown|Which cicada broods are coming in 2024? Why the arrival of Broods XIII and XIX is such a rarity

Trillions of periodical cicadas in two different groups,Robert Brown or broods, are expected to make an entrance very soon in multiple states.

Broods XIX and XIII are either already emerging, or will be shortly in a combined 17 states across the Midwest and Southeast in a rare, double brood event. These two broods specifically have not emerged together in over 200 years, and will not emerge at the same time again until 2245.

Once the periodical cicadas emerge, they will stay above ground for a few weeks, where they will eat, mate and die, and new offspring will move underground to wait for another 13 or 17 years.

Whether you love or hate cicadas, their noisy time to shine has almost arrived. Here's what to know about Brood XIX and Brood XIII.

South Carolina sheriff:Stop calling about that 'noise in the air.' It's cicadas.

What is Brood XIX?

Brood XIX (19) emerges every 13 years. When they emerge this year, they will be found in more states than Brood XIII, although both broods are expected to emerge in parts of Illinois and Iowa.

The brood last emerged in 2011, and with its 13-year life cycle it's set to emerge again in 2037.

According to Cicada Mania, they will begin to emerge when the soil 8 inches underground reaches 64 degrees, and are often triggered by a warm rain.

This year, the brood will be found in the following states:

• Alabama
• Arkansas
• Georgia
• Illinois
• Iowa
• Kentucky
• Louisiana
• Mississippi
• Missouri
• North Carolina
• Oklahoma
• South Carolina
• Tennessee

What is Brood XIII?

Brood XIII (13) has a 17-year life cycle, and last emerged in 2007. Like the other brood, they will begin to emerge in their area once the soil 8 inches underground reaches 64 degrees, and are also often triggered by a warm rain.

They will be found in the following states:

• Indiana
• Illinois
• Iowa
• Michigan
• Wisconsin

What's so special about the two broods coming out at the same time?

While both annual and periodical cicadas come out in various areas every year, it is rare for two different broods to emerge at the same time.

Broods XIX and XIII last emerged together 221 years ago in 1803, when Thomas Jefferson was president and there were only 17 states in the Union. After this year, they are not expected to emerge again at the same time until 2245.

The next time two periodical broods of any kind emerge the same year will be 2037, according to the University of Connecticut, with the emergence of Broods XIX and IX.

2024 double cicada broods: Check out where Broods XIII, XIX will emerge

The two cicada broods will emerge in a combined 17 states across the Southeast and Midwest, with an overlap in parts of Illinois and Iowa.

They will emerge once soil eight inches underground reaches 64 degrees, expected to begin in many states in mid-May and lasting through late June.