Discovering Species – Red-tailed Bumblebee

Who doesn’t like bumblebees? They’re colourful, small and fluffy, all the things we associate with cuteness, whilst also being a constant of sunny summer days. There’s also been a great increase in awareness in recent years about how vital they are for survival due to their pollination services. I love bumblebees, and have learnt a fair amount about their basic ecology and identification already, but came across a behaviour I’d never seen before whilst out on a walk in mid-August, which I found very exciting. It persuaded me to make the effort to learn a bit more, specifically about the Red-tailed Bumblebee (Bombus lapidarius).

I’d been seeing Red-tailed bumblebees all over the place since Spring – seemingly more of them than any other species. I loved watching this one on the borage in my little wildflower patch:

Identification

You can tell by the colouration (all black with a red tail), and full pollen-baskets that the bumblebee above is a Red-tailed bumblebee worker.

Similar-looking species this can be confused with include the Red-tailed Cuckoo Bumblebee (Bombus rupestris) which, according to the Bumblebee Conservation Trust, can be distinguished by its very dark wings (females) or grey stripes (males). Another way cuckoos can be distinguished from true bumblebees is their lack of pollen-baskets, but this requires a hand-lens (or maybe an excellent camera-lens!) to be able to see the hairs on the bee’s hind legs. In a nutshell, true bumblebee females have a shiny, hairless surface on their hind leg which is edged by hairs – this forms the pollen basket. True bumblebee males and cuckoo bumblebees have small hairs all over their hind legs, with no pollen baskets.

The Red-tailed Cuckoo Bumblebee is a parasite of the Red-tailed Bumblebee. The cuckoo queens lay their eggs in the cells of the true bumblebee nests, and allow the true bumblebee workers to raise them as if they were their own species. They may also kill the colony’s queen and take her place in the colony. This is why the cuckoo queens and workers lack pollen baskets (they have no need to collect pollen for themselves).

Red Shanked Carder Bee (Bombus ruderarius) is the other species in the UK which may be confused with a Red-tailed bumblebee. They also are black with red tails, but can most clearly be distinguished by having red hairs on their hind legs, rather than black. I have only seen this myself by using a hand lens – it’s very difficult to see this small detail when the bee is flying!

Males vs Females – There are three “castes” of bumblebees which can usually be distinguished from each other by sight: queens, workers and males.

Worker bumblebees (as in the video above) are always female. Males will also be seen on flowers feeding on nectar, but do not have pollen-baskets as they do not “work” to collect pollen. They also often look different to their female counterparts. In the case of Red-tailed bumblebees, the females are black all over except for their red tail. Males have yellow stripes at the top and bottom of their thorax, and yellow faces. I’ve also been told that the males tend to meander and look “lazy” compared to the busy workers!

Queens

There are a few ways the queens can be distinguished from the other castes (workers and males). Red-tailed bumblebee queens have the same colouration as the workers (black with a red tail), and this is common amongst other bumblebee species. The easiest way to recognise a queen is the size: queens are noticeably bigger than males and workers and resemble the typical bumblebee we all imagine. I found listed on NatureSpot the length comparisons for Red-tailed bumblebees:

Males: 14-16mm

Workers: 11-16mm

Queens: 20-22mm

Distribution and Habitats

As suggested by seeing so many about, Red-tailed bumblebees are known to be an abundant species, and widespread throughout the UK. This is possible due to their ability to use a range of habitats – they can be found anywhere that there are flowers for them to feed on.

Bumblebee Ecology Basics

Bumblebee ecology is super interesting. They are eusocial, meaning they work together as a colony, with the different castes having different roles. Queens (large, female bumblebees ready to lay eggs) emerge from hibernation in early Spring and find a nest site (this is why they are often seen flying slowly or walking on the ground – they are looking for a suitable hole to start making a nest in, often a disused small mammal burrow). There are lots of interesting details, but very briefly, the queens lay eggs and collect pollen and nectar whilst they develop. The first brood which hatches are all females (workers). The workers then collect pollen and nectar to feed the next brood and the queen takes on a solely egg-laying role, and the colony grows. Later in the season, “male eggs” as well as females are laid. Some of the new females towards the end of Summer will develop into new queens, which the males will mate with. The males and the rest of the colony die at the end of the season, with only the new queens surviving. The new queens find places to hibernate over the winter (often underground), to emerge the following Spring to form new colonies.

This August, I was walking in the woods and noticed a tiny flash of red at the edge of the path. I looked a bit closer and saw a little furry tail wiggle its way out of the ground backwards..!

I was fascinated to watch this new queen starting her winter “home” and feel really lucky to have stumbled across her!

Most of the ecological information above is also applicable to other bumblebee species. Other bumblebees will of course have different identifying features, distribution and habitat preferences.

It makes sense for there to be a lot of Red-tailed bumblebees about as they are a widespread and abundant species, but I feel like I’ve seen a lot more this year than previously (they are easy to identify which makes them stand out, but I remember seeing many more Buff-tailed and White-tailed bumblebees last year). I’ve been enjoying seeing them about and would be interested to know if anyone else feels like they were particularly abundant this year!