8 things you need to know about the giant wasps invading your yard

8 things you need to know about the giant wasps invading your yard
Male cicada-killer wasp, left, and female, right.

These guys are the jumbo jets of wasps.

They’re called cicada-killer wasps, and they’re drawing more concern from homeowners in the Omaha area the last few summers, said Jonathan Larson, an entomologist with Nebraska Extension for Douglas County. They emerged here in the last few weeks.

They are Nebraska’s biggest wasp, with females measuring 2 inches and males 1½ inches, big enough to send gardeners and backyard barbecuers ducking for cover.

“They are quite menacing,” Larson said. “People see them and are frightened.”

But the wasps are generally harmless to people. Still, the Nebraska Extension office is getting plenty of calls about the intimidating insect. Here’s what you need to know.

Do they sting?

Females have stingers but are too busy building their nests and killing cicadas to bother you. If you were to accidentally step barefoot on a female, she might sting you. So best not to go barefoot if you see their nests in the yard.

Also good to keep pets away from them. Males are territorial and will dart at you like a dive bomber, but they don’t have stingers. The males spend most of their time drinking nectar and trying to mate.

What’s with the scary-sounding name?

They’re called cicada-killer wasps because that’s what the females do. The females attack, sting and carry paralyzed cicadas to the wasps’ underground nests. The females lay eggs on the cicadas, which become food for the wasp larva.

Why does it seem like there are more of them?

Cicadas, their prey, develop in the root system of trees. Removal of wooded areas for residential or commercial development could send cicadas to suburban and urban yards, which in turn would draw the wasps.

What do the wasps look like?

Males and females are boldly marked with yellow stripes on a black body. The bold markings are intended to keep predators away.

Do they swarm?

Other wasps often live in colonies, but not the cicada killers. There is just one wasp per nest, but there can be a dozen or more of the nests in a yard, so you can end up with plenty of them buzzing around. They like to build their nests in full sunlight, and you’ll often see them along sidewalks, patios and flower beds.

Can they damage lawns or gardens?

The females dig extensive tunnels that are part of their nests. A burrow at the base of flower or other plant may disrupt its roots system. Lawns can be damaged by their digging, especially when tunnels are extensive and soil is left in mounds on the grass.

Are these wasps beneficial?

Yes, because they keep keep the cicada population in check. An overpopulation of cicadas can lead to tree damage.

What can I do to control the wasps?

The wasps like loose, dry soil to build their nests, so keeping your lawn or garden wet will help keep them away. Also, anything you can do to make your grass thicker will help, because that will make it harder for them to dig into the soil for nest-building. Thicker mulch on flower beds also helps. For a short-term fix, a powdered insecticide containing carbaryl can be sprinkled into the nests. If the wasps aren’t causing problems, it is best to just to leave them be. They usually disappear by late August.

Sources: Nebraska Extension, gardeningknowhow.com

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