What bumblebees look for in a nest site
Nest sites vary between bumblebee species. Most of the more common species prefer dry, dark cavities and nests can turn up in a variety of unexpected places.
Some nest underground, in places such as abandoned rodent holes, under sheds and in compost heaps. Of those that nest above ground, some make nests in thick grass, while others make nests in bird boxes, lofts and in trees. One of the species which nests in bird boxes and lofts is the Tree bumblebee, Bombus hypnorum. With this species you may often see 'swarms' of bees flying around the nest (see the video at the bottom of this page). This is perfectly normal, and these are male bees, which often fly around nests, waiting for queens to come out so that they can mate. Male bees cannot sting, so please don't be alarmed if you see this.
When searching for a nest, the queen will investigate the environment using both sight and smell. When she finds a potentially suitable site she will investigate by going into the hole. If it proves unsuitable she will continue searching until she finds a nest site. The distinctive low-flying zig zag flight of a nest-site searching queen is seen in spring and is very distinctive.
In gardens, bumblebees tend to nest in relatively undisturbed areas such as shaded corners. Some will also nest under structures such as sheds. They do not like to nest in areas with prolonged exposure to the sun as this can heat the nest too much.
Bumblebee nests vary in size depending on the species and time of year. A well-established nest may contain up to 400 bees. Honeybee hives typically contain 50,000 bees so bumblebee nests are very small in comparison.
How do I provide nesting sites for bumblebees?
You can help bumblebees by providing them with somewhere to nest.
The first step of course is to provide lots of the right kinds of flowers in spring. At this time of year the nest-searching queen will be attracted to gardens where she can find plenty of food to help her produce her first batch of eggs. For information on the best flowers to plant for bumblebees, visit our Bee kind tool.
Once she is ready to lay, the queen will start looking for a nest site. She flies low over the ground in a zig-zag pattern, stopping to investigate holes in the ground, or piles of leaves.
It can be quite difficult to encourage bumblebees to nest in a specific place - even specially designed nest boxes have limited success. However, here is a design to build a suitable nesting site in case you want to give it a go.
What you need:
- A flowerpot (> 20cm in diameter)
- A piece of slate/ tile
- A bit of tube or pipe
- Sink the upturned flower pot into the ground and use the slate/ tile to cover any drainage holes to keep the rain out.
- Run a hose or pipe underground to the pot, leaving a prominent entrance. Be sure to make drainage holes in the pipe.
- Finally, fill with a generous handful of nesting material, such as old bedding from a pet mouse, guinnae pig, etc.
Inside a bumblebee nest
Inside a bumblebee nest will be a queen bee, who lays almost all of the eggs. Around her, she will have a number of worker bees, who help to look after the nest, collect food, and raise new offspring.
Unlike the distinctive honeybee nest, which has tightly packed hexagonal cells for raising offspring and storing honey, the inside of the bumblebee nest can appear quite messy and disorganised.
You might also find a number of dead bees and grubs near the nest entrance. This is because worker bees will remove dead and dying bees from the nest to keep it clean and free of disease.
What to do if you find a bumblebee nest
If you find a bumblebee nest, consider yourself very lucky! They aren't very common, and can be difficult to find.
We recommend that if you find a bumblebee nest, it is best to leave it alone and avoid disturbing it. If you do approach close to it, be sure not to breathe on the nest, as this can make the bees behave defensively, and they may sting. Please note that though bumblebees are not generally aggressive, they might get aggravated if you interfere with the nest itself. They don't form swarms, but you may see a cloud of male bees flying outside the nest, as in the video below. They should just get on with life and do their own thing - doing a wonderful job of pollinating plants, wildflowers and your vegetables. Even the very largest nests produce very little "traffic" in and out, so you won't see threatening numbers of bees at any point during the summer.
If the bees are living under your shed, and are coming up through holes in the floor, then this is probably because it's the easiest way in and out for them. If you make a different hole, from the outside of the shed, and then block up the hole they were using, then they should happily take to their new route.
Bumblebee nests don't live for long, so the nest should die naturally within a few months. After that time, the new queens will have flown from the nest to hibernate in the soil elsewhere.
It is possible that a different bumblebee queen will find and use the same hole next year. The old nest will die in the autumn though, and all the bees will have left or died. If you don't want bees in the same place again you can block the entrance to the nest up after it dies down to prevent a new queen finding the nest site in later years.
Staff from Bumblebee Conservation Trust are unable to move bumblebee nests, however if you really need to move the nest or would like more information on re-routing nest entrances, click here to view our guide to moving bumblebee nests.
Below is a video is a 'drone cloud' - a group of male bumblebees hovering outside a nest waiting for females to emerge so they can mate. This behaviour is only found in the Tree bumblebee (Bombus hypnorum). The males have no sting, so please do not be alarmed if you see this.
"We are facing a fundamental problem with the decline of bees and other pollinators. They have an absolutely crucial role in pollinating many of our important crops - without them we will face higher food costs and potential shortages."
Professor Douglas Kell
BBSRC Chief Executive