Tree bumblebees in Grantham

Bumblebees are fascinating insects and I have been meaning to learn more about them for a long time. I’m not sure that it doesn’t have something to do with the fact that they looks quite so similar to colourful bats up close… there is something about their furry round bodies which is rather reminiscent!

It is still very early in the season but most of our UK species respond to conditions rather than dates and when the sun is shining and the weather is mild, many hibernating species will come out of torpor and begin their spring routines. I have recorded pipistrelle bats in flight over the last week; the birds are certainly thinking about nesting with the early species such as long-tailed tits gathering nesting materials; and there was quite a gathering of bees on a very early flowering blackthorn on Monday lunchtime.

I managed to get a couple of photographs of this bumblebee and decided that this would be the first ID on my path to learning more about these species. And it looks as though I picked quite a good one – my tentative ID of a tree bumblebee (Bombus hypnorum) was confirmed by helpful tweeters @sbd08simon and @ed_p_wildlife. Apparently there is no other bee which this species can easily be confused with – the colouration is just black and buff-brown with a white tail. No coloured bands! This bee has quite a simple pattern compared with the multitude of variations which other species seem to manage! This guide from Bumblebee Conservation gives a great introduction to identifying bumblebees.

Tree bumblebee Bombus hypnorumAlthough I am, as already confessed, no expert, I believe this must be a queen out foraging and potentially searching for a nesting site. The queens emerge in spring (usually March or April) and scope out potential nesting sites before laying their eggs. About six weeks later, the eggs hatch and the entirely female workforce splits into teams, some foraging for the colony, others staying in the nest to do the housework. Later in the year, ‘reproductives’ are produced – these are virgin queens and/or drones. The drones will die after mating with a female but the queens will hibernate through the winter and emerge when the temperatures warm up in the spring and the cycle can begin again. I would therefore suppose that my bumblebee feeding in February is a queen freshly emerged from a relatively short winter’s sleep.

Tree bumblebees are so called because of their habit of nesting in trees – either in woodpecker holes or more frequently, in nest boxes. Like most species, they have adapted to inhabit the world we have created around them and can also be found nesting in houses, in soffit boxes and similar features. Some other species of bumblebee will occupy similar niches but the preference for these tree (or tree-like) nesting sites is most notable in the tree bumblebee. Many other UK species will nest underground and you can often see them bumbling into the undergrowth towards the entrances to their underground homes.

Tree bumblebees are a relatively new additional to the UK’s fauna – they first appeared in Wiltshire in 2001 and have been spreading north every since. It is believed that they are natural colonisers which have established under their own steam, much like the collared dove which was a rare vagrant until the 1950’s when they were first recorded breeding here and now grace most garden bird tables across the UK. The invasion of the tree bumblebee appears, so far, to be benign with no observed impacts upon existing native bee populations and its spread appears to be continuing with the first recording in Scotland last year.

I have recorded my sighting here – the data gathered from recordings around the country can be used to study this species and describe its distribution around the country.

If you want to read more about the tree bumblebee, there is a very informative factsheet available from Bumblebee Conservation.

Tree bumblebee Bombus hypnorum on Blackthorn Prunus spinosa

Spring flowers

Spring flowers are beginning to appear everywhere! The weather has turned colder now again but spring is still certainly on the way – here are just a few of the species to be seen around Grantham at the moment, there will be many more to come!


Blackthorn (Prunus spinosa)
This is a typical component of hedgerows throughout the country and there are plenty of examples of it aroung Grantham. Most of them are not yet in flower but this specimen growing on its own beside the river seems to be at the head of the pack! Start looking out for the white patches in the hedgerows around now – blackthorn comes into flower before its leaves unfurl which makes for a beautiful spring sight with a mass of creamy white blooms.

You may know blackthorn as sloe – the small purple plum-like fruits which can be used to make sloe gin, jam and, well, little else. These are generally harvested after the first frost of autumn so it will be a long time before these flowers produce ripe fruits.

Blackthorn (Prunus spinosa)


Flowering cherry (Prunus spp.)
This is another non-native but very welcome spring flower. There are two native species of cherry tree – wild and bird – but the majority of those you are likely to see around are ornamental varieties. This one is growing on Sandon Road, outside of the construction college but you can see them flowering in gardens and public spaced throughout Grantham, including the town centre.

You might notice how similar the cherry and the blackthorn flowers are – they are in fact in the same genus, the prunus. This genus includes all of the cherries including familiar fruits – cherry of course, apricot, peach and plum, as well as almonds which are effectively the stone you might be familiar with and not, therefore, a true nut.

Cherry blossom viewing is one of the highlights of the year in Japan – they have blossom viewing parties and events and there are even forcasts which predict when the blossom will be in its fullest glory around the country, depending upon geographic location and weather conditions. I’m not aware that this has caught on to the same extant here in Grantham, but the flurry of whites and pinks certainly do cheer up the town as you walk through.

Cherry (Prunus spp.) blossom


Snowdrop (Galanthus nivalis)
One of the most widely recognised spring flowers, these are generally considered to be a naturalised rather than a native species. They are found as natives across Europe and certainly fend for themselves in this country but the first recorded colonies were in the 1770’s *. It is possible that some plants are native however, especially in the south of England, however these on the bank of Grantham College are almost certainly planted. One of the earliest spring flowers, they are probably coming to an end now as the weather begins to warm.

You do get many cultivars and ornamental varieties too – if you want to see a nice display, Easton Walled Gardens, just along the A1 south of Grantham, has a snowdrop week once a year, however you’ll have to wait until next year for the next one!

Snowdrop (Galanthus nivalis)


Lesser celendine (Ranunculus ficaria)
This is a small native species in the same family as the buttercup – the Ranunculus family. The small yellow flowers are another characteristic of early spring and grow in abundance due to their habit of spreading by rhizomes as well as seed. They are most apparent on warm sunny days such as this as they are only open during daylight and close up when it is dark or overcast.

They can be found in many places – they are often present in woodlands or along the bases of hedges where they can spread out into adjacent grasslands. They bloom early in the year, preceding the trees coming into leaf – when they grow beneath a wooded canopy, spring is the time when they will get the maximum amount of light. The plant will die back in May and then remain dormant for much of the remainder of the year.

These flowers were growing alongside the snowdrops on the bank of the college on Stonebridge Road.

Lesser celendine (Ranunculus ficaria)

As an extra bonus, which I didn’t even notice until uploading this picture, is a tiny little ivy-leaved speedwell (Veronica hederifolia) growing within the celendine patch – see closeup below! You can see where it derives its name from too and, in this case, the latin is a very good reflection of the English. Ivy-leaved speedwell (Veronica hederifolia)Hedera is the ivy family and folia derives from the latin for leaf; hence ivy-leaved. Veronica is the family name of the speedwells.. This species generally flowers in April – May but it must have found particuarly favourable conditions settled in amongst the celendines.