Bumblebee Aware for May 2020
One of the advantages of being forced to live through “a month of Sundays” when the weather has been enjoyable is that we have been able to spend a lot of time in our gardens. It may be because of this that we have been much more aware of bumblebees than usual. More and more flowers are starting to bloom and pollinators are collecting food actively. There have also been many times when we have seen queen bees flying low to the ground at the base of hedges and in odd corners of the garden looking for nesting sites.
There is a link between the abundance of flowers in an area and the number of nests to be found. Studies have shown that the distance that a species travels to forage is related to their average body size and the number in the colony. For example the Early bumblebee only travels about 500 metres from her nest whereas the Buff-tail will go 1500 metres on average. The bigger the colony, the more food it needs and the further it must travel to collect. This applies even as changing seasons bring a sequence of different floral opportunities. An area with large distances between food sources will have a worse effect on the smaller pollinators when planting practices change.
Honeybee colonies are easy to locate because they live in hives and also because you can see streams of bees entering and leaving them. To protect the colony, there are dedicated, armed guards at the entrance. Bumblebees are less well organised and are less able to defend their families and so the nests are hidden and not given away by obvious comings and goings. The main threats are from rodents and also from cuckoo bumblebees that will follow a queen to her nest and then take it over.
Bombus pascuorum, or the Common Carder Bee is a beautiful blond with a rich ginger thorax and so cannot be mistaken for any of the black and yellow, or black and red, species in this area. They fly between March and October. Nests are made usually on the surface in tussocky grass or at the base of hedges, and may produce up to 150 individuals. This small output from the founding queen means that the species is more vulnerable to attack than more productive ones. The long tongue allows tubular flowers such as gorse, comfrey, clover, white dead nettle, and buddleia to be targeted but they have a wide range to feed from.
The easiest way to decide which plants to buy for your pollinator-friendly garden is to visit the Garden Centre and watch the bumblebees. Their free advice is available throughout the year.
Adrian Doble (Bumblebee Conservation Trust) May 2020