Bumblebee Conservation Trust
School of Biological & Environmental Sciences
University of Stirling
FREQUENTLY ASKED QUESTIONS
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You’re very lucky if you have found a bumblebee nest – many people have them in their gardens, but not many people ever come to realise it!
Bumblebees thankfully are not at all aggressive and only rarely sting when handled roughly. They might get aggravated if you started to interfere with the nest itself, but not if you’re just passing by. They don’t swarm and certainly don’t ‘attack’ like wasps or honey bees. They should just get on with it 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.
The colony only lasts one summer – it will have finished by September/October at the latest – (quite possibly much earlier) and all of the bees will have gone. It’s possible (although not particularly likely) that a different bumblebee queen will find and use the same hole next year.
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.
As mentioned above, bumblebees are not at all aggressive, seldom sting, and are very easy to live with. We very much hope that people will only try to move nests that are in a particularly inconvenient location. Underground nests will be more difficult to move, as you’ll create a considerable amount of disturbance as you dig down to the nest. However, if it’s outside and underground then there should be no reason to move it….
To move a nest safely it’s best to do it in the dark – when all of the bees will be ‘asleep’. They might buzz a bit… but they wont fly in the dark, so you can do it reasonably safely.
The ideal for the bees would be to find a shoe box, or something similar – perhaps larger for a particularly big nest. Put dry grass or dry moss in the bottom of the box to rest the nest in. Make a 2cm hole in the side, and cover it with selotape of some kind of bung. Then pick up the nest at night (either wearing long-sleeves and gardening gloves, or perhaps using a spade), pop it in the box, and shut the lid. Try to keep the nest upright, otherwise their honey pots will spill. Put the nest somewhere sheltered, and put a board or something waterproof over the top to keep the rain out. It’s also best to avoid direct sunlight if you can.
Once you’ve moved them, and the bees have settled down, just remove the selotape/bung. The bees might take a little while to adjust, but they should take to their new home pretty well.
Bumblebee nests grow throughout the season, and produce new males and queens in autumn. Throughout the life of the nest a large number of smaller worker bees help the nest to grow by collecting nectar an pollen – these are the bees that you see out and about in summer. These workers only live 2 weeks or so, and then sadly die. It’s therefore quite normal to see a small number of dead bees in the garden. So long as you are still seeing live bees in the area, then it’s unlikely to be something new that we should be worrying about.
Bumblebees, like many insects in fact (and humans!) sometimes suffer from a number of different parasites which live inside them. These parasites can make the bees appear slow and sluggish, perhaps drunk even! Again, sad as this may seem, it is a natural process that has been going on for many many years, and is not at the root of the problem. Equally, bumblebees may sometimes seem very lethargic just because the weather is cold – but they will recover when it warms up.
Having said all of the above, if anyone begins to notice large numbers of dead bees across a large area, coupled with very few live bumblebees in the area then it’s just possible that a disease outbreak has occurred in your area. If you are seriously worried that this may be happening then please collect a sample of the dead bees, package them securely, and post them to the above address.
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 queens will be attracted to gardens where they can find plenty of food to help them produce their first batch of eggs. Once she is ready to lay, she 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.
Several bumblebee species regularly nest in gardens. Some species, such as B. pascuorum, nest on the soil surface in a shady corner where a pile of dryish leaf-litter has gathered. Others, such as B. terrestris and B. lucorum, like to nest fairly deep underground but cannot dig holes themselves so they use existing cavities. Naturally they often use abandoned rodent holes, but in gardens they will opportunistically nest under sheds, patios and paving slabs, in compost heaps, and in rockeries. B. pratorum in particular seems to like nesting in shallow cavities under stones rockeries, but this species also sometimes nests well above ground in bird nest boxes. It seems likely that most gardens provide nesting opportunities for bumblebees.
If you want to encourage bumblebees to nest in your garden, it is easy and cheap to provide suitable sites. All they want is a dark, draught-free and fairly dry cavity with a small access hole, preferably placed in a shady, quiet corner of the garden, such as the bottom of a hedge, or under a shrub. A paving slab placed over a football-sized cavity in the soil is pretty effective. Just make sure there are one or two gaps for the bees to get in. Similarly, a piece of thick plywood placed on the ground amongst long grass seems to be quite attractive as a nest place for B. pascuorum (although it needs to be left in place for a year or two). Alternatively, use a few old bricks and/or pieces of plank to construct a chamber roughly 15 cm x 15 cm by 10 cm high, again leaving a small gap (about 2 cm wide) at ground level for the bees to get in. Build it in a quiet corner of your garden, throw in a few dried leaves, dried moss, Kapok, or bits of an old bird nest (which the bees use to insulate their nest), and leave well alone. The more nest sites you can provide, the more likely it is that one will be found and used. If it isn’t used by bumblebees it hasn’t cost much! And it will certainly provide a home for other insects and perhaps voles and mice.
It has long been suspected that bumblebee queens may use the smell of an old rodent nest as a cue to the presence of a suitable nest hole. It may help the take-up rate of your artificial nest sites if you bait the nest with rodent droppings and old nest material (for example from a pet mouse or gerbil).
It is noticeable that once a nest site has been used once, it is very often reoccupied the following year. It seems likely that queens searching for nest sites use the faint smell of an old nest as a good indication that the site is suitable for nesting. Thus it is best to leave your nest sites in place for many years; the longer the better, for once they are eventually discovered by a queen and used for nesting, they are then likely to be used over and over again.
A number of companies now offer bumblebee nest boxes of various types. These vary enormously in design and construction, but all consist of some sort of box with an entrance hole, either designed to be placed on the ground or buried in the ground. These boxes are often quite expensive, and in our experience they are rarely used by bumblebees. This may be because they are not placed in a suitable position; they need to be in a shaded and undisturbed corner of the garden. The entrance hole needs to be at ground level and easily discovered by a queen. However, given that it is easy to make nest sites for bumblebees for free, we are not yet convinced that commercial boxes are a good investment.