Wasp, hornet or yellow jacket? Tell them apart by the nest

What is the difference between a wasp, a hornet and a yellow jacket?

All three are wasps, and all three build with the same material: paper wasps, hornets and yellow jackets "construct nests of a paper-like material containing finely-chewed wood fragments and salivary secretions" [1].

Telling them apart by the insect alone is harder than it sounds, because the colours overlap: the European paper wasp "has yellow and black markings much like a yellowjacket" [1].

One body clue does hold: paper wasps have a waist "that is very thin", which distinguishes them from hornets and yellow jackets [1]. The nest is easier to read.

How do you tell them apart by the nest?

Look at where it is, and whether you can see the cells.

• Paper wasps: open and umbrella-shaped. They build "in protected locations, such as under eaves, gutters and ledges, or in attics, barns or sheds" [1].
• Hornets: enclosed, and usually out of reach. A bald-faced hornet builds "a large, gray nest resembling a bloated football", attached to a tree, bush or the side of a building [1]. European hornets use cavities instead, and "most commonly nest in tree hollows", sometimes in wall voids [3].
• Yellow jackets: hidden. Nests are "often constructed belowground in old chipmunk/rodent burrows", and also in "stone walls, crawlspaces, attics, and behind exterior siding of buildings" [1].

No nest in sight, but wasps streaming in and out of one hole in the lawn or one gap in the siding? That is the yellow jacket answer.

Why are yellow jackets suddenly everywhere in September?

Because the colony is at its peak and the food it wants has changed.

"During late summer/early fall, yellowjacket colonies are nearing maturity and huge numbers of workers are out foraging for food for the developing queens" [1], and late-season nests "often contain thousands of individuals" [1].

With insect prey becoming scarce, they "scavenge widely for other sources of nutrition", and are "particularly fond of sweets" [1][2]. Nothing has turned them mean; there are simply more of them, and what they want is on the picnic table.

So this is the season for covering food and drinks outdoors, keeping lids on trash cans and raking up fallen fruit [1][2].

Are they more aggressive in autumn, or just closer to the nest?

Distance from the nest decides it, not the month. Away from the nest, foraging workers "are seldom aggressive and usually will not sting unless provoked", and UK entomologists advise walking away calmly rather than swatting [1][2].

At the nest it is a different insect: "when the nest is threatened the colony may launch a coordinated assault on the perceived threat" [1].

Anyone concerned about a reaction to a sting should contact a healthcare provider.

Do wasps reuse the same nest next year?

No. "In Kentucky and other states with cold winters, wasp, hornet and yellowjacket colonies die off naturally once the weather turns cold" [1], and abandoned nests "are not reused and soon disintegrate" [2].

So a grey papery shell on the eave in February is a leftover. New queens do keep choosing the same sheltered corners, which is why one porch gets a nest year after year.

What are mud daubers?

Mud daubers — called dirt daubers across much of the South — are wasps too, but each female builds alone with mud rather than paper, so there is no colony and no nest to defend. Mud daubers: are they dangerous, and why are they here?

How do you get rid of a wasp nest?

It depends on whose nest it is, and that is the first thing to settle.

• A small paper wasp nest — an open, umbrella-shaped comb under an eave, porch ceiling or railing — is the smallest job, especially in spring when only the founding queen is on it.
• A yellow jacket nest is usually hidden in the ground, a wall void or an attic, with a single busy entrance, and it can hold thousands of wasps by late summer.
• A hornet nest is the large, enclosed gray paper ball in a tree, shrub or under an eave.

The yellow jacket and hornet nests are the ones not to tackle. Blocking a ground or wall entrance, pouring water in, or burning a nest usually sends the colony out through another route, sometimes into the house. A wall-void nest can chew through into a room.

What are cicada killers?

Cicada killers are the huge wasps — up to about an inch and a half long, black or rusty with yellow bands — that dig holes in lawns, bare soil, sandy banks and the edges of sidewalks in mid to late summer. The female catches a cicada, paralyzes it and drags it into her burrow as food for her young; a mound of loose soil at each hole is the sign.

They look frightening but rarely sting. The males patrol and dive at people, but males have no stinger. The females can sting, but they are not defensive the way yellow jackets are and seldom do unless handled or stepped on barefoot. Each female digs her own burrow, so there is no nest to defend. Thick, healthy turf and fewer bare, sunny patches make a lawn less attractive to them.

Do wasps die after they sting?

No. Wasps, hornets and yellow jackets have a smooth stinger and can sting again and again. It is the honey bee whose barbed stinger catches in skin and tears away, so a honey bee usually stings once. That is part of why a disturbed yellow jacket nest is so much more dangerous than a single bee.

What are "ground bees"?

Two very different insects get the name. Yellow jackets nesting underground show a single hole with a steady stream of wasps flying in and out, and they defend it hard. Mining bees are gentle, solitary bees that dig many small holes with little mounds of soil in bare, sunny patches of lawn in spring; each female has her own burrow, they rarely sting, and they are gone in a few weeks. Thicker turf makes a lawn less inviting to them.

What are sweat bees?

Sweat bees are small bees, many of them a shiny metallic green, that land on skin to lap up sweat for the salt in it. That habit is where the name comes from, and it is why they turn up on arms and necks on hot summer days. Most nest in the ground, digging narrow burrows in bare or thinly grassed soil, and many live alone rather than in a colony.

They are not aggressive. A sweat bee usually stings only when it is pinched against the skin, trapped under a collar or brushed off roughly, and the sting is mild next to a wasp's or a yellow jacket's. They are also pollinators. Watch the hole to tell them apart from yellow jackets: small bees coming and going from many scattered burrows are sweat bees or mining bees; one busy entrance with a steady stream of wasps is a yellow jacket nest.

Why not knock the nest down yourself?

Because the two nests people most want gone are the hardest to reach.

Hornet nests "are often located out of reach, requiring use of a ladder and/or other specialized equipment", and UK's advice is that "it is often best to call a professional pest control firm" [1]. For yellow jackets, "it is usually prudent to call a professional, especially when accessing nests requires use of a ladder, or is otherwise difficult" [1].

A nest inside a wall carries its own trap: do not seal the gap the wasps are using, because that can cause them "to chew their way inward and emerge indoors" [1].

How does Liberty handle wasps, hornets and yellow jackets?

Differently, and the nest decides that too.

Wasps are a plan pest, handled on regular pest control visits. Plans cover wasps on the first floor of your home. Your Service Specialist knocks down and treats wasp nests on the first floor of your home, like under eaves, porch ceilings and railings.

Hornets are not. They aren't part of Liberty's plans, so hornet treatment starts with a free inspection. Your Service Specialist treats the nest, whether it hangs in a tree or shrub, sits under an eave or is inside a wall.

Yellow jackets are not either. They aren't part of Liberty's plans, so yellow jacket treatment starts with a free inspection. Your Service Specialist treats the nest at its entrance, whether it is in the ground, a wall or an attic.

When to call a professional

Call when the nest is somewhere you cannot reach or cannot see into: high on the house, up a tree, down a hole in the lawn, behind the siding. Those are the cases where UK Entomology says to call a professional rather than work off a ladder [1]. Call too when a nest sits beside a door, a walkway or somewhere children play.

The inspection settles which insect it is and where the nest really is, and that decides the rest — first-floor wasp work on your regular pest control visits, or a hornet or yellow jacket nest after a free inspection.

Common questions

What is the difference between a wasp and a yellow jacket?

A yellow jacket is a kind of wasp, so the real comparison is with a paper wasp. Paper wasps have a very thin waist and hang open, umbrella-shaped nests under eaves and ledges; yellow jackets nest out of sight, belowground or inside walls, crawlspaces and attics [1].

How can I tell a hornet nest from a paper wasp nest?

By whether it is closed. A bald-faced hornet nest is a large, grey, enclosed shell that UK Entomology compares to a bloated football, hanging from a tree, bush or a building [1]. A paper wasp nest is open underneath, so the cells show [1].

Why are yellow jackets so bad in late summer?

Two things at once. Colonies are nearing maturity with huge numbers of workers foraging, and late-season nests can hold thousands of individuals [1]. Meanwhile insect prey gets scarce, so they scavenge widely and are particularly fond of sweets [1][2].

Do yellow jackets really nest in the ground?

Often, yes — belowground in old chipmunk or rodent burrows, or beneath rocks, gutter splash blocks and landscape timbers [1]. A steady stream of wasps in and out of one hole in the lawn is the usual first sign — worth finding before someone mows over it.

What is a mud dauber?

A solitary wasp with a long, thread-thin waist that builds nests of mud instead of paper — tubes, lumps of mud cells, or old nests reused. Dirt dauber is the same insect under another name.

Do mud daubers sting?

Rarely. Mud daubers live alone and have no colony to defend, so they sting only when grabbed or trapped against skin. An old mud nest with round holes in it is already empty.

How do you get rid of a wasp nest?

Start by working out whose nest it is. Small paper wasp nests under eaves are the easiest; yellow jacket nests in the ground or walls and large hornet nests should not be blocked, flooded or knocked down, because the colony comes out another way.

Do cicada killers sting?

Rarely. The males that dive at people have no stinger, and the females seldom sting unless handled or stepped on. Each female digs her own burrow, so there is no nest to defend.

Do sweat bees sting?

Rarely, and mildly. A sweat bee usually stings only when it is pinched against the skin. It lands on people for the salt in sweat, not to attack.

Are wasps, hornets and yellow jackets covered by a pest control plan?

Wasps are, on the first floor of your home, and your Service Specialist knocks those nests down and treats them on regular visits. Hornets and yellow jackets are not plan pests; each starts with a free inspection, because what the treatment must reach depends on the nest.

Sources

1. University of Kentucky Entomology. Michael F. Potter. "Controlling Wasps, Hornets, and Yellowjackets" (ENTFACT-620). https://entomology.mgcafe.uky.edu/ef620 ↗ (opens in a new tab)
2. University of Kentucky Entomology. Michael F. Potter. "Foraging Yellowjackets" (ENTFACT-634). https://entomology.mgcafe.uky.edu/ef634 ↗ (opens in a new tab)
3. University of Kentucky Entomology. Jonathan L. Larson. "European Hornet in Kentucky" (ENTFACT-600). https://entomology.mgcafe.uky.edu/ef600 ↗ (opens in a new tab)