September surprises

You’d probably expect to see less bees flying as summer gives way to autumn, and it’s true that the leafcutters, wool carder bee and many mining bees have gone. But if you have late flowering blooms you may see plenty of bumblebee queens stocking up on nectar before searching for a cosy winter hideaway and common carder bee workers are still out in force. Wooden posts drilled with small holes, may be busy with large-headed resin bees plugging their nests with tiny pieces of grit and stone and gluing it together with tree resin. And if you’re near flowering ivy (yes, mature ivy is smothered in tiny white flowers later this month) don’t miss the Ivy mining bee. This short-lived solitary bee emerges just before the ivy flowers and disappears shortly after. And this month marks 20 years since the ivy bee was first recorded in the UK.

We decided to included honeybees in our guide this month for two reasons:

1. You’ll see lots on flowers in your garden because there aren’t many flowering trees in September, and it’s their last chance to collect nectar and turn it into their winter stores of honey

2. It’s easy to confuse ivy bees and honeybees when they are both on the ivy flowers. So carefully examine the photos above and ID notes below.

Tips for IDing September bumblebees:

  • Tree bumblebees (Bombus hypnorum) – if you’ve been bee spotting all summer, you should be quite adept at identifying tree bumblebees by now. But they can be confused with similar sized common carder bees as both have a gingery thorax. The tree bumblebee sometimes looks like it has a bald patch and it’s abdomen is blacker and it’s bottom (or tail) is always white. They usually have two generations each summer so the ones you see flying this month will be new queens, workers and males from the second 150-strong colony. The only difference in appearance between the queen, males and workers (known as the three castes) is their size. Queens are a larger 15mm, males 13mm and workers 11mm.
  • Common carder bees (Bombus pascuorum) seem even more common at this time of year. Queens that began producing worker bees in April are now producing new queens and males so they are flying too . The castes all have the same ginger pile on their thorax, but their fluffy bodies can vary in colour from light to dark brown. They are the smallest bumblebees flying in September.
  • Red-tailed bumblebees (Bombus lapidarius) – easily recognisable with their gorgeous red butt, but unfortunately this bee is a less frequent sight for many of us these days. In the south, queens can produce a second colony of up to 300 bees, so it’s this second generation there are now flying. The queen is one of our biggest bumblebees: measuring 17mm, she can look quite intimidating with her velvety black body and striking red tail. Workers are a smaller version of the queen(12mm), but males (12mm) have cute yellow facial hair and yellow bands on their bodies.
  • Buff-tailed bumblebees (Bombus terrestris) our most common bumblebee, has two generations in the summer and even a third which flies during the winter in the south of England. However at this time of year, I find them much less ubiquitous than common carder bees. This may be because only the huge mated queens (18mm) are flying stocking up on nectar and looking for a suitable nesting site to raise a new colony in the south, or further north, the queens are stocking up on nectar and looking for a suitable hole to overwinter.

How to ID September solitary bees:

  • Ivy mining bee (Colletes hederae) – one of the highlights of autumn is being able to spot an ivy mining bee. To the untrained eye, they can look deceptively like a honeybee, especially as they are both found on mass buzzing around nectar-rich ivy flowers in the south of England and Wales. However, look closely and you’ll see the ivy bee sports a quiff of orange hair on its thorax and its body has much more defined and shiny segmented bands in buff and brown alternate colours. Ivy bees are also a little smaller (10mm) than honeybees (14mm). Ivy bees are the last solitary bee to emerge in the UK. The males first, in late August, or early September, and females a couple of weeks later. They can gather nectar (and the females pollen) from a variety of late flowers before the ivy flowers, but the easiest way to see them is to inspect the tiny white ivy flowers. Ivy bees belongs to the Colletes family, which mine into the ground to make their nests – often next door to each other in very large numbers – and they line their nest with a cellophane-like waterproof and fungus-resistant substance, which is why Colletes are also called plasterer bees. If you have a south-facing slope with light soil you may see hundreds, even thousands, of these bees emerging from their individual nests. It is easy to forget that they are solitary bees. As you can see on this great video from the Hampshire & Isle of Wight Wildlife Trust. Fascinating fact – the ivy bee was only described as a separate species in 1993 and wasn’t discovered in the UK until 2001 in Dorset. Unlike the other newcomer, the tree bumblebee, ivy bees aren’t thought to have spread to the north of England. But if you see one beyond the Midlands, please report your sighting to BWARS (Bees, Wasps and Ants Recording Society).
  • Common yellow-faced bee (Hylaeus communis) – these small (5mm) predominately black bees with tiny yellow spots or a triangle on their face has been a familiar sight in gardens since mid summer (if you’ve been able to spot such a diminutive bee). The females have been known to nest in bee hotels/boxes if the hole dimension is small enough. They also plaster their nests and unlike other bees collect pollen in a special stomach, called a crop, and regurgitate it to make a semi-liquid mixed with pollen to feed the larvae. Fascinating fact: They have been observed blowing bubbles of nectar to evaporate the water. This is known as water homeostasis and it concentrates and thickens the nectar/pollen mixture making it tacky like honey. The bees eggs and larvae ‘stick’ to its surface, unlike many other solitary bee larvae which ‘sit’ on top of the more solid pollen mixture. Here is a video of the bubble blowing. (I’m yet to see any of this behaviour myself, so thanks to Nurturing Nature and Api:Cultural for the info and footage).
  • Large-headed resin bee (Heriades truncorum) – I have seen these industrious, small (5mm) solitary black bees with a strange wide head plugging their nests with tiny bits of grit in pre-existing holes in wood. It looks like they are making a mosiac from the grit which they stick together with resin they collect from trees. If you live in the south-east of England (where they are commonly found), and install wooden logs, or a post, drilled with holes a few milimetres wide, you may see them making mosiacs in your garden next summer. They have also been known to use bee hotels/boxes. If you live further north, take a look here at their fascinating behaviour. And with warmer summers across the UK, they could be coming to a green space near you especially where yellow ‘weeds’ such as ragwort, sow thistles and hawkweeds are left to grow.
  • Common furrow bee (Lasioglossum calceatum) – these small solitary bees with an elongated black shiny body have been flying since early spring. So there is no excuse for not recognising them (although I still have problems with ID). The ones you will be seeing now are males and females that were born in July and can fly until October. Fascinating fact: These burrowing bees can display primitively eusocial behaviour, which means the early flying females in warm climates are actually queen bees that in early summer produce workers. These worker bees will collect nectar and pollen for the new females and males that are born later in the summer.

How to help bees in September

  1. Plant flowers that bloom this month to provide important late sources of nectar and pollen. Sedum, Michaelmas daisy, dahlia, fushsia, Devil’s bit scabious, and wild marjoram are all good, and don’t forget Common sneezeweed (Helenium autumnale), the solitary bees favourite, according to Rosybee nursery’s fantastically helpful research . A particular fav in our garden is Helianthus ‘Lemon Queen’ a slug-proof sunflower, and of course, the Geranium Rozanne is still going strong! For the long-tongued bumblebees, black horehound, salvias and buddleia are still flowering, and hemp agrimony is good in damp soil.
  2. The best late forage for short-tongued honeybees and ivy bees without a doubt is ivy. But ivy only flowers when it is mature and that can take 11 years! So if you have any sprawling ivy that needs a trim, please don’t cut it back until after it’s flowered this month.
  3. If you only have a window box, Mexican fleabane (Erigeron karvinskianus), trailing nasturtium and bird’s-foot trefoil are still flowering. Add sedum and annuals such as cosmos and snap dragons. If you grow herbs in pots and window boxes, let the mint and oregano keep flowering.
  4. Gather seeds Store them in labelled paper bags in a cool, dry place for sowing or scattering next spring. Or, just scatter them around your garden now while the soil is still warm. Lightly rake the soil, scatter the seeds, cover them with fine soil and firm down.
  5. Leave parts of the garden undisturbed, as ground nesting bumblebee queens may be looking for a snug place to overwinter and don’t chop down old, dead stems that solitary bees may have laid eggs in.
  6. Ditch the weed killers and pesticides. 
  7. Take semi-ripe cuttings if you are patient and want to propagate heathers, ivy, Mahonia, Escallonia and flowering-currents. The cuttings should be ready to pot on next spring.
  8. Create a bank of sand mixed with some clay soil against a south facing wall for mining bees which like to burrow into sand. It only has to be about 400mm deep. Create steps in the sand as some bees like to nest vertically and others horizontally. The clay will help the bank to keeps its shape after the bees have tunnelled into it. If you’re lucky you may get ivy mining bees nesting in it this autumn next door to each other in large neighbourhoods.
  9. Drill holes in blocks of wood – 10mm, 8mm, 6mm and 4mm diameters and up to 30 cm deep (although some bees only need a depth of a few centimetres to nest in) – and screw them to a sturdy support. Drill holes in existing structures such as fence posts, or dead trees. Large-headed resin bees, scissor bees and yellow-faced bees may take up residence, but probably not until next year.
  10. Provide a source of water for thirsty bees. This can be a shallow bowl or saucer with stones or pebbles in that the bees can stand on while they are drinking. Bees can’t swim!

For information on IDing and helping bees earlier in the year see my Bees to See in August blog here,  Bees to See in July blog hereBees to See in June blog here,  Bees to See in May blog here and Bees to See in April blog hereBees to See in March blog here.

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