Wasps & Yellowjackets in the San Gabriel Valley
Most stinging visitors in SGV yards are paper wasps or yellowjackets. Here's how to tell them apart, where they nest, and when a nest needs a pro.
- Paper wasps: slender, long legs, open umbrella-shaped nests
- Yellowjackets: stocky, bright yellow-and-black, aggressive
- Yellowjackets often nest in the ground or wall voids
- Both sting repeatedly (unlike honeybees)
- Most defensive in late summer and fall
What they look like
The two wasps you'll meet most in the San Gabriel Valley are paper wasps and yellowjackets. Paper wasps are slender with long, dangling legs and a pinched waist, usually brownish with yellow markings. They build the familiar open, umbrella-shaped honeycomb nests you see hanging under eaves, in patio covers and inside grill lids.
Yellowjackets are stockier, brightly banded in yellow and black, and far more aggressive. They fly fast, hover around food and trash, and nest out of sight — in the ground, in wall voids, or under decks. Hornets are simply large wasps; the bald-faced “hornet” is actually a type of yellowjacket. Unlike honeybees, wasps can sting again and again.
Wasps & Yellowjackets fast facts
| Feature | Detail |
|---|---|
| Looks like | Slender (paper wasp) or stocky yellow-black (yellowjacket) |
| Where found | Eaves, patio covers, ground, wall voids |
| What they do | Sting repeatedly; defend the nest |
| Active when | Spring–fall; most defensive late summer |
| Concern level | Painful stings; serious for allergic people |
Where they live
Paper wasps favor sheltered, open spots: eaves, soffits, patio covers, door frames, mailboxes and unused grills. Their nests stay small early in the season and grow through summer. Because the nests are exposed, they're easy to spot once you know to look up.
Yellowjackets are the hidden ones. They nest underground in old rodent burrows, in wall and attic voids, and under decks and sheds — and a single colony can hold thousands by late summer. You'll often see a steady stream of insects coming and going from one small opening before you ever find the nest.
Signs of a problem
The clearest sign is steady wasp traffic to one spot — a corner of the eaves, a hole in the lawn, a gap in the siding. A few wasps patrolling the yard in spring is normal; a defined flight path in and out of one opening means a nest.
Yellowjackets also crash outdoor meals, hover around trash cans and soda cans, and turn up at hummingbird feeders. Activity that ramps up sharply in August and September — when colonies peak and food gets scarce — is the classic SGV pattern.
How to get rid of wasps: paper wasps vs. yellowjackets
To get rid of wasps, first tell paper wasps from yellowjackets. An exposed paper wasp nest under an eave can often be left alone, or removed while it is small, but a hidden yellowjacket nest in the ground or a wall is a job for a licensed operator. UC IPM notes paper wasp nests should not require treatment unless they are near people, while yellowjackets scavenge food and grow defensive as their colonies get larger through the season.
- Identify the wasp and the nest. Paper wasps build open, umbrella-shaped nests with exposed cells under eaves; yellowjackets nest in the ground, in wall voids, or in enclosed gray paper nests with one entrance.
- Take away what draws them. Cover food and pet food, cover soda cans outdoors, keep garbage in sealed cans and empty them often, and pick up ripe fruit.
- Trap early in the season. Protein-baited water traps work best on queens in late winter to early spring; lure traps attract mainly western yellowjackets. Set traps away from where people gather.
- Leave exposed paper wasp nests alone unless they are near people. UC IPM notes paper wasp nests should not require treatment unless they are near people; a small early nest is a smaller job.
- Call a licensed operator for hidden yellowjacket nests. Underground and wall nests can run far from the entrance, sprays may not reach them, and a plugged entrance can push wasps to chew a new way out.
When it is our job, we treat the nest directly, remove the nests we can reach, and knock down the spots wasps keep rebuilding on. If a nest is high, inside a wall, or near anyone with a sting allergy, do not disturb it; give us a call. Our pest emergency guide covers what to do in the meantime, and you can ask for a free quote any time.
Do wasp repellents work? Essential oils, fake nests and traps
Some wasp repellents have real evidence behind them and most do not. In a 2013 field study, blends of clove, geranium and lemongrass oils completely blocked yellowjacket and paper wasp attraction to baited traps, while fake paper nests have no published study showing they keep wasps away.
| Option | What the evidence says | Verdict |
|---|---|---|
| Essential-oil blends (clove, geranium, lemongrass) | Of 21 essential oils field-tested, 17 showed significant repellency, and blends completely blocked worker wasps from baited traps (Zhang and colleagues, 2013) | Promising, but tested at traps, not across a whole yard |
| Single essential oils | Repellency varied from oil to oil in the same study; blends worked best | Short-lived; reapply and do not expect a force field |
| Fake paper nests | No peer-reviewed study we could find; the idea relies on territorial paper wasps avoiding a rival nest | Unproven; yellowjackets nest out of sight and would not see it |
| Wasp traps | Lures with heptyl butyrate attract mainly western yellowjackets; protein-baited water traps work best on queens in late winter to early spring (UC IPM) | Useful early in the season; they reduce numbers, not nests |
| Covering food, soda and garbage | Removes what yellowjackets scavenge (UC IPM) | The repellent that always works |
| Aerosol wasp and hornet sprays | Can be effective on exposed nests but must be used with extreme caution; even freeze-type sprays are not guaranteed to stop every wasp (UC IPM) | For small exposed nests only; never a hidden ground or wall nest |
Bees vs. wasps: who removes a bee hive?
A honey bee swarm or hive is not an exterminator’s job. A swarm is a cluster of bees between homes and usually moves on within a day or two; an established colony in a wall, eave, chimney or the ground is a job for a beekeeper or bee-removal specialist who can take out the bees and the comb. Do not seal the opening with bees inside, because trapped bees and abandoned comb draw other pests. If the insects are lean, bright yellow and aggressive around food and trash, they are probably yellowjackets, and those are ours.
Sources
- UC IPM Pest Notes: Yellowjackets and Other Social Wasps (University of California)
- Zhang and colleagues, Essential oils and their compositions as spatial repellents for pestiferous social wasps, Pest Management Science (2013)
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Quick Answers
Quick Answers.
What's the difference between wasps and bees?
Wasps have slender, smooth bodies and can sting repeatedly; bees are rounder and hairier and most sting only once. Wasps are predators and scavengers drawn to meat, sugar and trash, while bees collect pollen. If it's at your soda or trash, it's almost certainly a wasp.
Are paper wasps or yellowjackets worse?
Yellowjackets. They're far more aggressive, nest in large hidden colonies, and will swarm to defend a disturbed ground or wall nest. Paper wasps usually sting only if you get close to their nest. Both stings hurt, and either can be serious for someone with an allergy.
Why are wasps worse in late summer?
Wasp colonies grow all season and peak in August and September, just as their natural food runs short. That's when large numbers turn to human food and trash and become most defensive — so late summer is when most stings and nest calls happen.
Should I remove a wasp nest myself?
Only a small, early paper wasp nest you can reach easily, and only if it is near a door, a play area or someone with a sting allergy; UC IPM notes paper wasp nests should not require treatment unless they are near people. Yellowjacket nests in the ground or a wall are not a do-it-yourself job, because they can erupt all at once. If the nest is large, hidden, high up or near anyone allergic, leave it alone and call a pro.
How do you get rid of a wasp nest?
We treat the nest directly, remove accessible nests, and knock down the spots wasps keep rebuilding on. For hidden yellowjacket nests in walls or the ground, we treat the opening so the colony is eliminated rather than just scattered.
How do I keep wasps from coming back?
Keep trash sealed, clean up fallen fruit and pet food, and seal gaps in eaves, siding and screens where they start nests. Checking eaves and patio covers in spring and knocking down new nests early stops a small one from becoming a summer problem.
What is the best wasp repellent?
Taking away what draws them: covered food and soda, sealed garbage and picked-up fruit. Beyond that, the best-tested option is an essential-oil blend of clove, geranium and lemongrass, which blocked wasps from baited traps in a 2013 field study. Nothing sprayed on a patio keeps wasps away for long.
Do fake wasp nests work?
There is no published study showing they do. The idea is that territorial paper wasps avoid building near a rival nest, but a paper bag has none of the scent or defenders of a real colony, and yellowjackets nesting in the ground would never see it. It does no harm; just do not count on it.
What smell do wasps hate?
In field tests, clove, geranium and lemongrass oils, and especially blends of them, repelled yellowjackets and paper wasps from baited traps (Zhang and colleagues, 2013). The effect is local and short-lived, so it helps around a table, not across a yard.
Do wasp traps work?
They reduce numbers when used early. UC IPM notes protein-baited water traps work best on queens in late winter to early spring, and that lures with heptyl butyrate attract mainly western yellowjackets. Place traps away from where people gather, since they draw wasps toward them.
How do I get rid of yellowjackets in the ground?
Leave it to a licensed operator. UC IPM notes underground nests can be far from the visible entrance, so sprays may not reach the wasps, and a disturbed ground nest can erupt all at once. Do not plug the hole or pour anything into it; keep people and pets away from the flight path until it is treated.
Who removes a bee hive?
A beekeeper or bee-removal specialist, not an exterminator. Honey bees are pollinators, and a colony in a wall needs the comb removed along with the bees. A swarm hanging on a branch usually moves on within a day or two.
What should I do if I get stung?
Walk away from the nest area right away, and do not swat or run if a wasp lands on you; brush it off gently. Seek medical help immediately for trouble breathing, swelling of the face or throat, or many stings, since UC IPM warns that multiple stings can be serious.
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