14 March 2023
By Kevin Henry, Bumblebee Conservation Trust volunteer in Carmarthenshire
For over 10 years, volunteer Kevin has been trying to encourage bumblebee queens to nest in his garden by providing a variety of bumblebee nest boxes.
In general, artificial nest sites (except for bird boxes) aren’t used much by bumblebees, as queens are very picky. But Kevin has found success with lots of trial and error! We chatted to him about his fascinating experience, as well as his ‘top tips’ for attracting nest-searching queens to your outdoor space.
Hi Kevin! What inspired you to start making bumblebee nest sites?
There are many factors, such as habitat loss and pesticides, that are having a detrimental effect on bumblebee populations. The most common species are also struggling, in part, because many people strive to have a tidy, immaculate garden. ‘Nest searching’ queens in spring will find it more difficult to find a suitable nesting site in these immaculate gardens. Although my garden is, thankfully, far from perfect, I decided to leave areas to become wilder and to create a few mini habitats. This certainly helped, as I have had many nests over the years, but I found my interest, possibly obsession, with bumblebees and their nesting habits growing!
I was fascinated to watch nest searching queens in my garden entering old rodent holes, disappearing under leaf litter, going under my shed and most of the time, reappearing a couple of minutes later and flying off or carrying on their search.
I decided to set up some nests to observe them in more detail and to find out a little more about what they were looking for, how long they would spend in a potential nest site, and to see if they actually took up residence in these artificial nests.
I first started setting up nests in my garden in Hertfordshire and more recently in my garden in south west Wales.
Kevin labels his nest boxes with different colours so he can easily make notes in a journal he keeps, monitoring bumblebee behaviour
Can you tell us about the different nest sites you’ve tried and how you set them up?
I first tried setting up nests under flowerpots, under stones, in depressions in soil and so on, but these were never really successful.
I now use a mixture of commercially made bumblebee nest boxes* and adapted bird boxes.
I tend to place the nest boxes in areas which are popular with nest searching queens. This spring, I will be placing nest boxes along the bottom of a bank, under hedges and other shrubs, next to a shed and on top of a wall.
Within these boxes I place nest material, usually kapok, on a bed of pet wood chippings or shredded paper. I generally form a ‘ball’ of material within a depression in the wood chippings. I experiment with the size, normally the size of a tennis ball, and often add dried leaves and moss.
I usually construct at least one nest from dried moss, raked from the lawn, which are often attractive to Common carder bumblebees (Bombus pascuorum). An old mouse nest can be added but the jury is still out if this is really necessary.
I believe the interior of the nest box is very important and I spend much time setting up the nests and experimenting with material, although I do avoid man-made materials as the queens could get tangled up in these.
It can be frustrating to watch a queen enter a box with a beautifully constructed nest inside and reject it within a few minutes!
Kevin creates a cosy nest site using natural materials such as kapok, dry moss, and wool, on a bed of pet wood chippings
What have you done to make your artificial nest sites more attractive to the nest searching queens?
I place the boxes in areas where queens have been observed, often moving boxes if I think there is a better location.
I try to make the entrances as noticeable as possible. I use moss, soil, old mouse nests, dried grass, bricks and small logs to make the area look natural, but always make sure there is a distinct entrance, leading to the interior.
Kevin adds natural materials around his nest boxes, but always makes sure the entrance remains obvious to nest-searching bumblebee queens
What interesting bumblebee behaviour have you seen?
Observing occupied nest boxes is the most exciting part of the ‘project’.
It is very exciting to watch a queen carry out an orientation flight after accepting a nest box, and to watch her flying around the area to ‘memorize’ the location. Some queens will set up a nest very quickly, often bringing in pollen the next day, others will hang around for several days, entering the box regularly, but still nest searching in the area.
The most fascinating thing I’ve seen is the usurping of occupied nests by other queens. I have noticed that occupied nests often attract other queens that are nest searching. These queens do not always enter the nest straight away, but come and go over a few days. I presume they are attracted by the scent of the other ‘foundress queen’.
If these queens enter the nest, they are often sent packing by the occupying queen but often fights to the death will ensue. In 2022 I observed thirteen dead queens in one nest box! Buff-tailed bumblebees (Bombus terrestris) and Tree bumblebees (Bombus hypnorum) seem to be the species that I see carrying out usurping the most.
These usurping queens, if successful, will have a ready-made nest to settle into, although it is a risky strategy!
It is also amazing to watch the first small workers the queen has reared, leave the nest to start foraging in my garden and beyond.
Do you have any top tips or advice for people who want to encourage bumblebees to nest in their garden?
My first tip is obvious I guess – plant suitable flowers, shrubs and trees in your garden or planters. Without the flowers, there is no pollen or nectar for bumblebees.
Also, don’t forget to leave areas a little untidy, especially under hedges or shrubs, or construct a compost heap, and you could possibly sit for hours watching the comings and goings of a bumblebee colony.
When it comes to nest boxes, a good place to start would be to put a bird box on a shed, tree or similar, and place some nest material inside. Do not place in a location that will receive sun all day, as this could cause overheating. I find reducing the entrance size will keep birds from entering. This simple type of nest box may well attract Tree bumblebee queens (Bombus hypnorum), as well as a couple of other species.
How has creating and monitoring your nest boxes affected your wellbeing?
Bumblebee queens appearing in my garden are my sign that spring is finally here, probably my favourite season. I find it a great way to relax and switch off from the day job. There is nothing better than coming home from work and going into the garden to watch the bumblebees on a beautiful spring evening! Sitting quietly making observations is also a great way to see other wildlife.
At this time of year, the only problem can be that the garden and household chores take a back seat from the bumblebees!
*A note on bumblebee nest boxes: Although it is possible to buy bumblebee nest boxes with a ready-made bumblebee colony inside, we do not recommend these. It is much better to follow Kevin’s lead and wait for wild bumblebees to find your garden. Commercial bumblebee nests, marketed at gardeners and nature lovers, pose a threat to our natural bumblebee populations through competition for food and potential transference of disease and pests.
