Some groups of periodical cicadas come out every 17 years; some groups come out every 13 years, and some are annual arrivers. In Lancaster and York, and across the state of Pennsylvania, cicada nymphs are expected to emerge en masse from the ground in late May or early June. This is the year for the 17-year brood to emerge.

The time of the cicada emergence (and impending swarm) will depend on how warm the temperatures get. Cicadas prefer to emerge when soil temperatures reach 64 degrees, according to Penn State Extension.

There are 8 different periodical cicada broods in Pennsylvania. Brood X (10) is expected to arrive in our area this May-June. We’ll see the adults from the eggs laid in the ground in 2004.

We expect billions of cicadas to emerge from the ground. So why does this happen and what are these insects? Will it seem like a plague of insects? Are cicadas dangerous?

Let’s find out:

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