Wasp, hornet and yellowjacket nests: Utah's late-summer season

Paper wasps

Paper wasps build open, single-comb nests where you can see the cells, under eaves, deck railings, porch lights and play sets. They're usually less aggressive than yellowjackets but will defend a nest near a doorway.

Bald-faced hornets

Bald-faced hornets build enclosed gray paper nests, often football-sized, hanging from branches, shrubs, sheds and eaves. Colonies can be large and defensive, so these are best left to a professional when they're near people.

Yellowjackets

Yellowjackets hide their nests, usually in shallow chambers in the ground or inside wall voids. You don't see them until someone mows over the entrance, which is why they cause so many multiple-sting calls in August and September.

Which nests to leave alone

Nests aren't all bad; wasps eat a lot of garden pests. A small nest high in a tree at the back of the lot can be left. The ones to deal with are near entries, decks, play areas, paths and anywhere someone with a sting allergy spends time.

• Leave: high in trees, far from paths
• Call: by doors, decks and play sets
• Call: in the ground along paths or lawns you mow
• Call: in walls, soffits or attics

Wild About Utah describes bald-faced hornets hanging gray paper nests in tree branches, yellowjackets usually building in shallow underground chambers, and Polistes paper wasps found statewide. USU Extension adds a useful detail for traps: fruit-juice baits work for European paper wasps in mid to late summer, while yellowjackets respond to heptyl butyrate lures, so a trap baited for the wrong insect catches very little. Traps thin foragers around a patio; they don't remove a nest.

Stings and allergies

Most stings cause local pain and swelling. Seek emergency care for trouble breathing, swelling of the face or throat, or dizziness. Anyone with a known allergy should stay well away from nests and removals.

Sources

• wildaboututah.org
• extension.usu.edu