CHESTERFIELD, Mo. – In Missouri, cicadas are just starting to emerge but just down the street, they’re already coming out by the thousands and soon it’ll be thousands going into millions across the St. Louis area. And while they don’t do much harm, there is one exception.

Chris Hartley of the Butterfly House says the most likely reason for the difference in cicada emergence from place to place is temperature…cicadas need the soil temperature to be at least 64 degrees a couple of inches down before they’ll emerge.

“So some areas are going to get more sunlight; they’re going to get more afternoon sunlight. It’s going to be warmer; it’s going to be cooler; that’s why it kind of seems to be going in spurts every now and then, but we’re going to have some consistently warm days from now on, and that’s going to really get the emergence going,” Hartley said.

Hartley said the maximum emergence will probably be in early June. And while cicadas don’t bite or sting and are clumsy flyers, they can harm very young trees. If you have any concerns at all, it can’t hurt to net your trees. Those with less than a year in the ground are the only ones that could potentially be killed.

“We’re talking about billions of cicadas so a young tree could potentially get most of its branches affected so that could overwhelm the tree,” he said.

Trees with over a year in the ground won’t be harmed, but you may notice a temporary change.

“You might see the very tips of branches start to turn down and droop as the females lay eggs in them. That could happen to any tree of any size. That’s not going to kill a tree, it’s just going to look unsightly for a little while,” said Hartley. “It is killing off the growth at the very tip of the tree but that is just a little bit of new growth on your tree.”

Hartley says cicadas go for the new growth because it’s easier to get into. And once the eggs hatch, the nymphs will come out and go immediately underground, where they’ll stay until 2037.