Cicadas are expected to overwhelm the United States: their appearance may be provoked by warm rains in April or May

It's been a long time since cicadas have interrupted our travel plans, but it looks like this spring may be the time to watch out for them. For the first time since 1803, two broods of cicadas that have been under

That means the flashy flying cicadas will be in trees in many states, and even here in the Midwest. Both broods are expected to show up in Illinois and Indiana, so if you're traveling in those states, you may experience some unpleasant noise from the bugs," krocnews.com reports.

Periodic cicadas don't appear often - once every 13 or 17 years, to be precise - and when they do, their populations number in the millions or even billions. This year, fate has it that two broods will emerge from the ground at once, which will be the first time in two centuries.

This year, broods XIII and XIX will appear. Brood XIII was last seen in 2007 and is expected to appear in Iowa, Wisconsin, and possibly Michigan. Brood XIX was last seen in 2011 and could appear in those states, but is expected to appear in Alabama, Kentucky, Missouri, Mississippi, North Carolina, Arkansas, Georgia, Louisiana, South Carolina, Virginia, and Tennessee.

When will they be available?

According to an article on CBS News, warm rain could trigger their emergence in late April and possibly early May. The cicada tracking site Cicada Mania claims that the bugs will emerge from the ground, probably when the soil 8 inches below the surface reaches a temperature of 64 degrees Fahrenheit, as this is the temperature that keeps them warm.

What kind of insects are they?

Cicadas do not harm people or pets. However, they can damage young trees if they lay their eggs on their branches. These insects should not be killed. Cicadas are an important element of the ecosystem. They are food for many animals, including birds, bats, and snakes. They also help enrich the soil when they die.