Written by Nancy Miorelli

Summer is upon us (in the Northern Hemisphere) and that means the wasps are out in full force. They’re doing their best work killing off pests and feeding their families but sometimes – their homes are a bit to close to ours.

You’ve seen the hubbub of wasp nest decoys on your Facebook and Twitter. Sounds simple – just put some sort of fake wasp nest around your home and BAM – no other wasps will want to build their nest there.

So does it actually work?

Well – not to burst your bubble, but probably not.

The Target Species

These fake nests are designed to mimic paper wasp nests. However, this gets complicated because what we call “paper wasps” and what science calls “paper wasps” is a kind of a linguistic mess.

Common names like “Yellow Jacket”, “Paper Wasp” and “Hornet” are difficult because the name corresponds to types of wasps that build certain types of nests but doesn’t have much scientific classification or taxanomic bearing. For the sake of this article – we are going to lump all these paper nest building wasps together. The following subfamilies all have members that are capable of building paper nests (Polistinae, Stengastrinae, Vespinae).

But to make matters more complicated, not *all* members of those subfamilies make paper nests. For example some “yellow jackets” DO NOT build paper nests. They prefer to nest in the ground so hanging anything from your trees is not going to affect ground nesting species in the slightest. Moving on from them …

The Wasp Life Cycle

Now that we’ve established that “wasp” is a messy term – we’re just going to keep going with it. Many eusocial wasps have the following generalized life cycle. This is important, because wasps don’t generally return to the same nesting site that they were born as the colony completely dies off except for a new mated overwintering queen. And in spring, it’s her job to find a new nesting site. Here’s the gist of the cycle:

1. New queen awakens from her overwintering beauty sleep in spring and finds a new place to make a nest.
2. She begins construction and produces the first wave of sterile workers.
3. The colony grows and the roles shift. The queen is responsible for laying eggs and the workers are responsible for nest maintenance, defense, and getting food.
4. Fall comes, and a new queens are chosen. They mate and look anywhere they can for safe warm place to overwinter.
5. The current queen dies and the colony starts to collapse. All the workers die off.
6. Spring rolls around and an overwintering queen wakes up from her peaceful slumber. She looks for a place to make her new nest.

Okay – Fine … And the Decoys?

Probably don’t work even though some of the DIY knitted ones are pretty cute. There are, unfortunately, no peer reviewed studies done of the topic. However, there is mounting anecdotal evidence that the decoys don’t work. Why? Because we have evidence from real wasp nests.

That anecdotal evidence would be wasps that have built nests right next to each other.
Example A:

Other wasps straight up build new nests on top of other species’ old nests
Example B:

And sometimes queens of one species will overwinter in an old abandoned nest of a completely different species.

Here’s a quote from a friend who works in pest control about all the different nests he’s found together!

Also, when I was back to work on pest control in late May in MN (USA), I started keeping an eye out for developing nests and noticed that the number of baby nests seemed way out of proportion to the number of mature nests when late summer rolls around. The record-setting house had two Dolichovespula maculata nests, a Dolichovespula arenaria nest, and a Vespula alascensis nest under the deck (all within 20 feet of each other) plus a Vespula consobrina nest by the driveway about 100 feet away from the 4-nest cluster under the deck.

James Kopco

Basically – wasps are looking for a few criteria.
They want to be warm, dry, and protected. Normally they’d hang out in tree hollows or under large leaves, or under large tree branches, but people’s yards often provide ample habitat. Roofing, gutters, old sheds, big trees, all provide for these new queens.

If there was an old nest there in the way and no one is there now to defend it? Well, the problem is easily solved by just building on top of it.
Or the place that has all the right criteria and there’s a neighboring nest next door – oh well. There’s room enough for two.

There is mounting anecdotal evidence that wasps just don’t really care if there’s another nest nearby or even an old nest from last year that hasn’t fallen down yet.

But My Friend Swears By It!

It’s very possible that they did put up a decoy nest and no wasps came the following spring. However – it’s important to look at *why*. Maybe the wasps found somewhere else first. Maybe the habitat changed slightly and now is no longer fitting. Maybe your neighbor used pesticides and its affecting your area as well. There’s a whole host of reasons for why a wasp may not want to build a nest right THERE this year. Furthermore, many new queens may start nests but those nests may not reach maturity due to a variety of environmental factors.

Basically – you don’t know if the wasps didn’t show up this spring because of your decoy or because of a random whole host of other factors. (This is why scientific articles are so important! They try and minimize the other factors so you can say X change had X effect).

By contrast – a photo of an active wasp nest next to a different (active or inactive) wasp nest shows that in at least some cases – wasps don’t give a poo if they’ve got neighbors. For me, evidence that it can happen far outweighs the claim that the decoys do anything but add a fake nest to your house.

Okay – I don’t want wasps tho … What Should I Do?

The best thing to do is to monitor your property regularly. You can usually take care of small nests by yourself without the need for a pest control. However, if you feel uncomfortable or the nest has gotten pretty big, you’ll want to call professional pest control agents to take care of the wasp nest safely. Wasps are beautiful animals but can definitely pose a threat especially to children and people who are allergic.

TL;DR

Wasps are unlikely to be deterred by fake nests. Although not officially studied in the scientific literature yet, wasps have been shown to make nests in close proximity and even build nests on top of old ones. Queens of one species have even been found to overwinter in the old nests of other wasp species. Best thing to do if you’re worried about wasps, is to continually monitor the areas around your house so you can address any inklings before there is a real problem.

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Reference Section

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Nancy is an entomologist living in Ecuador. When there’s not the quarantine due to the Covid-19 pandemic she is leading eco-tours of Ecuador. Currently, she’s teaching online entomology workshops.

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The next workshops is scheduled for August 14, 2020 and is about chemicals and ecology found in common arthropods.

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Photographic Evidence of Wasps Building on Top of Other Wasp Nests

1. Murdoch, J. 30 August, 2018. Posted in Insect Identification Facebook Group. Accessed 14 – July, 2020. Photo of two Dolichovespula maculata nests in close quarters.
2. Kopco J. 14 July 2020. Posted in the Entomology Facebook Group. Accessed 14 July, 2020. Commentary about queens, nest proximity, and new nest failures.
3. Kopco, J. 11 July, 2020. Posted in the Entomology Facebook Group. Accessed 14 July, 2020. Photo of Dolichovespula arenaria built on another nest.
4. Patterson N Jr. 29 April, 2020. Posted in Enthusiasts of Social Wasps Facebook Group. Photo of Polisted fusactus wasps in a Dolichovespula arenaria nest. Accessed 14 July, 2020
5. Prouty, T. 31-August-2018. Posted in Enthusiasts of Social Wasps Facebook Group. Commentary on photo posted y Murdoch J (2018). Accessed 14 July, 2020.
6. Rinehart, D. 21 June, 2020. Posted in The Entomology Facebook Group. Accessed 14 July, 2020. Post asking experts their opinion and evidence about the effectiveness of wasp nest decoys.