Nobody wants to live close to a wasps’ nest, so if wasps seem to return to your property every year to make it their home, you may be wondering what you can do to stop them.
To do this, it’s important to understand why wasps are drawn to the same places each spring, so in this post, we discuss the question, why do wasps keep coming back?
Wasps – an introduction
To understand why wasps keep coming back each year, let’s start by giving a brief overview of what we’re dealing with.
Wasps are insects that are closely related to bees and ants, and a huge number of species exist all over the world – over 100,000 have been described by science, and it is thought that many more have not yet been discovered.
Most people are familiar with wasp species such as yellowjackets and hornets, which are nest-building, social wasps. However, many other species of wasp are solitary and don’t build nests in the classic way that most people imagine.
Like bees, many wasps play an important role in pollination, and they are also an important species for controlling pests. Solitary wasps parasite pest species at various stages of their lifecycles, and social wasps such as yellowjackets are predators of pest species.
This means that like bees, wasps are an important and helpful species, so we shouldn’t automatically kill them whenever we see them.
However, due to the defensive behavior of nesting species such as yellowjackets – and their painful stings – it can be dangerous to allow wasps to nest near human habitation, in which case, if they build nests, their nests need to be removed.
Speaking of their stings, unlike bees, stinging wasps don’t lose their stinger and die after delivering a dose of venom, and often, a single wasp will sting multiple times.
However, while painful, the stings are not considered dangerous – except in people with an allergy to the sting, in which case it can cause the person to go into anaphylactic shock.
The lifecycle of wasps
Now we know a bit more about wasps in general, we also need to talk about the lifecycle of social, nesting wasps because this is key to understanding why they return each year.
Let’s take the yellowjacket as an example, since many other social wasps follow a similar cycle.
Everything starts with a single fertilized queen that has hidden out and overwintered in a protected place like the inside of a log, under bark, in leaf litter or somewhere similar.
As the weather begins to warm in spring or early summer, she emerges and looks for somewhere to build her nest.
Having found a spot, she lays around 30 to 50 eggs, and when the larvae hatch, she feeds them for about 18 to 20 days, after which they pupate.
After this, adult female worker wasps emerge. The queen then dedicates herself to laying more eggs while the workers take over caring for the larvae as well as expanding the nest.
As the colony matures, it can contain as many as 5,000 workers or more. The queen then also starts producing male wasps and new queens.
These important wasps remain in the nest and are fed by the workers, and the young queens concentrate on building up the stores of fat they will need to survive the coming winter.
Eventually, the males and queens leave the nest to mate. After mating, the males die, but the queens go off to find a safe place to spend the winter months.
Gradually, all the other wasps in the original colony – including the queen – die off.
However, the new queens will then re-emerge the following spring to build new nests and start the process again.
Why do Wasps Keep Coming Back?
Having looked at the lifecycle of wasps like yellowjackets, we can now dispel the common misconception that wasps from the previous year “come back”.
Since worker wasps and the queen that started the nest die off each year, it’s not possible for the same wasps to return the following year.
Furthermore, the new queens that emerge don’t usually return to their old nest, preferring to build a new one – although it’s not unheard of for a queen to take over a nest that that was built the previous year.
Instead, what happens is that when the new queens emerge, they set off to look for a suitable spot to start building their new colony, and a place that was attractive to young queens in previous years is likely to look similarly appropriate in subsequent years.
So while wasps won’t usually be drawn back to an old nest that hasn’t been removed, they will be drawn back to your house if the conditions remain as favorable as they were in the past.
So now let’s think about some of the things queen wasps look for when deciding where to build their new nest.
What attracts wasps to build nests?
If an area was suitable for building a nest one year and conditions don’t change, it will still be suitable for building a nest the following year – and here are some of the things a queen wasp looks for when choosing where to start her colony:
One of the first things wasps need to survive is water, so if you have bird baths, a pond or a pool in your yard, this will attract wasps. Wasps can detect evaporating water, and this will draw them in to check out its source.
Wasps are attracted by flowers, so if you grow colorful flowers in your garden, this will also attract wasps. Incidentally, this is why wasps will also be attracted to you if you wear bright colors, and they will also be attracted to brightly colored houses or rooms inside.
- Fruit trees
When trees bear fruit, the scent of the ripening fruit draws in wasps as it can be a potential food source. Queen wasps like to build their nests close to food, so if you have fruit trees near your home, it will make it more attractive to wasps.
- Other bugs
Since wasps like yellowjackets prey on other species, the presence of other bugs in and around your yard or garden will also attract them.
This may include grubs, larvae, aphids and other pest species, so the wasps may be doing you a favor by helping keep them under control – but sharing your home with wasps in return for this service might not be a price you’re willing to pay.
Most wasps build their nests primarily from chewed-up wood pulp, so the presence of wood nearby makes a site attractive for building a nest.
This might include rotting trees, but it can also include piles of firewood and even untreated wood decking.
- Food waste
Leaving food and drink out, especially sugary foods and drinks like soda, is a sure way to attract wasps to your home. They will also be attracted to open trash cans, which they can raid for tasty morsels.
- Protected sites for nests
An important consideration for any queen prospecting a site with an eye to starting a colony is finding somewhere with a protected location.
In the “wild”, this means looking for a suitable tree or perhaps a cliff face – but nowadays, human buildings also provide perfect nest-building opportunities.
As a result, the eaves of your house along with sheds, barns and even children’s play areas can seem the perfect place to build a nest for a newly emerged queen.
Finally, there are pheromones, the chemical signals wasps use to communicate with each other.
Even though the wasps from the previous year may all have died, the pheromones they left behind may still be detectable, and this is likely to draw in queen wasps to investigate who left the message.
how to stop wasps from coming back
Having understood what causes queens to return to your home year after year to build their nests, now we can think about the kind of things you can do to make your home more undesirable to them.
1. Remove water sources
The first thing you can do is remove water sources from around your home.
For example, you can temporarily empty any bird baths during the spring when queens are looking for nesting sites. Once the nesting period has passed, you can then fill them up again.
If you have a swimming pool on your property, make sure it’s covered over, especially during the nesting period. However, if you have an ornamental pond outside, unless you can empty it, there’s very little you can do.
2. Clear up rotting fruit from the ground
If you have fruit trees, the first thing to do is to pick up any rotting fruit from the ground as soon as it falls. For example, rotting apples on the ground are likely to attract wasps, so make sure there aren’t any available.
There’s not a lot you can do about fruit still on the tree – unless you want to knock it down before it ripens or just remove the tree entirely. However, fruit that’s still growing will be less attractive to wasps, so it’s not something you need to worry about as much.
3. Pay attention to sources of wood
If you have piles of firewood, try to cover it with tarpaulin so that wasps can’t get to it. Remove any other rotting wood or trees from your property and treat any wooden decking or outdoor furniture at the start of each spring so that wasps can’t use it for building nests.
4. Don’t leave food or drink lying about
When the spring arrives and the weather starts to improve, you may look forward to being able to eat outside again – but make sure you clear up all food and drink quickly after you finish.
5. Seal all trash cans
Make sure all trash cans are properly sealed so that wasps can’t get inside to see what they can find. Trash cans full of rotting food give off a strong odor that will draw in curious queens from miles around, so this is an important element to be aware of.
6. Spray likely nesting places with insecticide
If you have eaves or other areas of your home that wasps find particularly attractive, you may consider spraying them with insecticides.
This won’t deter the queens, but after they visit your home and land on the insecticide, they will fly off and die.
However, if you are ecologically minded, you might prefer to avoid this – since as we noted above, wasps play an important ecological role in both pollination and pest control, and killing off all the wasps in an area might not be a desirable outcome.
7. Properly remove nests from previous years
If a nest remains from the previous year, you should make sure it is removed properly. This means you need to take down the physical nest and also clean the area to remove any remaining pheromones.
This way, wasp queens won’t be drawn back to check out the interesting messages left in the area by previous generations.
8. Call in an exterminator
If, despite all your best efforts to make your home less attractive to wasps, they still decide to build their nest there, you may need to have the nest removed by a professional.
However, before you do this, consider how much danger it’s really causing. Because if it’s in an area where nobody usually goes, it might be safe to leave it there and just let the wasps do their thing for a few months since they won’t harm you if you don’t disturb them.
On the other hand, if the nest is in an area where you spend lots of time – or where children regularly play – it might be time to think about removing the nest for everybody’s safety.
Make your home less attractive to stop wasps coming back
So as we have seen, wasps don’t really “come back” to your home since, apart from the queens, they all die out each year.
However, other wasps will likely be attracted to the same kinds of places as wasps from previous generations, so the key to preventing wasps from building a nest near your home year after year is to make it as unattractive a place for them to live as you can.