How to make a bumble bee nest box
Bumblebees are larger and hairier than their cousins the honey bees, which makes them perfectly suited for colder climates. Their extra insulation allows them to venture out on cold days when honeybees stay tucked up inside. Bumblebees do not swarm and are not aggressive. Only female bumblebees can sting and they will only do so if they feel very threatened. Bumblebees play a vitally important role in pollinating crops that provide us with food to eat and the colourful flowers in our landscape. Without their ‘free bee’ service, many wildflowers could disappear.
Most gardens will attract bumble bees, especially with the right flowers providing pollen. See Flowers for Wildlife. Bumblebees are social insects and live in nests of up to 400 individuals. Each nest is ruled by a queen and lasts for just one year. This is different to honeybee hives which remain active for several years.
You can encourage bumblebees to nest in your garden by making an easily constructed artificial nest site. Using a tunnel and box, you can also observe the bees at work.
The plan shown below is a modification of an original design by F.W.L. Sladen – the father of bumblebee research (1876-1921).
The tunnel is made by hammering a 25-30mm iron rod through the soil. The soil must be well draining, otherwise the nest and its contents will start to decay. Remember that bumblebees usually make use of old vole nests or those of wood-mice; they choose dry sites, and warmth is also essential. The base of a south facing hedge would be perfect.
To make a nest in which you can observe the bees, you need first to construct a plywood box 100 x 100mm square and 200mm high with a lid that just rests on top. Position it at the bottom of the chamber with an entrance hole (near the base of the box) aligned to the tunnel (see Design 2, right). Such an arrangement is better insulated and offers more protection from damp. The cavity has to be deep enough to allow clearance between the wooden inspection lid and the cement slab.
Collect some fine dry grass for the nest itself with perhaps a little dried moss. Form it into a ball about 75mm across and place it in the nest chamber.
It is best to make this nest site before April, when the queen will be out and searching for a suitable nest site.
Once the bees are established, you can lift the box lid and see workers arriving with food and departing to forage, having off-loaded the food in the nest. You may also see some structural reorganisation in progress, but unless you are prepared to tease the nest ball apart a little (quite easily done) you won't see much else. Bumblebees are not easy to upset, so if you are patient and move slowly there is little chance of being stung – but do take care, especially if you are allergic to bee stings!