Tuesday 24 March 2015

Bees - it's all about shape and size!

There are an estimated 25,000 different species of bee on Planet Earth and they come in many different shapes and sizes. The largest bee in the world is 'Wallace’s Giant Bee' (Megachile pluto). She grows up to 3.9 cm long and has a wingspan of 6.3 cm. The smallest bee in the world is 'Perdita minima'. She is less than 2 mm long.
Bees also have different length tongues (proboscis). Tongue lengths vary from around 0.5mm to 15mm in Britain and Ireland
The size of the bee and the length of her tongue, are both of great significance when it comes to which flowers she is able to access when foraging for pollen and nectar. Honeybees tongues are around 6.3mm in length - so they can only access flowers with fairly short corollas.
If you have red and white clover on your lawn, you will notice different bee species on each. Short-tongued bees like honeybees and buff tailed bumblebees will go for the white clover, as it only has a short corolla. However, long tongued bumblebees, like B. hortorum (the Garden bumblebee) will forage on the red clover as it has a very deep corolla.
The deeper the corolla (flower tube) the greater the nectar reward tends to be….so short tongued bees often need to visit more flowers to get the nectar they need. 
The bee in the photo above is Bombus hortorum (the Garden Bumblebee). She has the longest tongue of any bee in the UK. If you see a black & yellow striped bumblebee with a white tail on your broad beans, and if her tongue is hanging out as she flies between each flower, it is highly likely to be this bee!

Some bee species resort to ‘robbing’ the nectar by cutting a hole in the base of the flower and accessing it that way. This is known as 'larceny'. When a bee commits larceny, the plant loses out because the bee completely bypasses the flower's pollen. Bombus terrestris (the buff tailed bumblebee) is a notorious nectar robber. Once she has made a hole, other bees and wasps use it to access the plant's nectar. Not a very fair exchange!

More about bumblebee flower preferences here  
Photos of largest and smallest bees here

Wednesday 11 March 2015

SO much more than a hole in the ground!

This tiny little hole (around 3mm in diameter) is the entrance to a solitary mining bee's nest. Each individual female solitary bee chooses an area of compacted sandy soil and digs her own tunnel. Some ground nesting bees choose south facing slopes, whilst others prefer to construct their nests amongst the roots of trees, in river banks, flower beds, or in your lawns  

After she has dug the main tunnel, the bee constructs a number of offshoot tunnels and at the end of each of these she fashions a small chamber. Each chamber is first waterproofed using an anti fungal, glandular secretion produced by the bee, then provisioned with pollen, which the bee has collected over many trips back and forth to the nest. Although most bees are not too fussy about where they source their nectar, they can be slightly more fussy when it comes to choosing pollen to provision their nest. Andrena clarkella, for instance (one of our earliest emerging ground nesting bees) relies exclusively on pollen from Willow (Salix spp.) So, it is of paramount importance that the right plants are in flower during the nest provisioning period.

Once she has provisioned the chamber with sufficient pollen and a little nectar, the female solitary bee lays a single egg in each chamber. When this process is complete, she fills in the entrance to the tunnel and may then go on to construct a few more nests before she dies. She is on the wing (above ground) for approximately 4 - 8 weeks. 

When the eggs hatch, the larvae will feed on the pollen before pupating. After they have pupated they remain beneath the ground till the following spring, when they emerge as adult bees, mate, and start the cycle all over again.

So, next time you see a little hole in the ground like this…..make time to stop and watch for a while. You will be enthralled and enchanted by what you see!

Here (below) are two of the more common solitary bee species you might see making their nests in these tunnels. The orange coloured bee is a Tawny mining bee (Andrena fulva)  and the black and grey bee is an Ashy mining bee (Andrena cineraria).

You may also notice small yellow and black striped bees (like the one in the photo at the bottom) buzzing around the holes. These are Nomada species (cuckoo bees) who nip in and lay their own eggs in the nests of the solitary mining bee. When the nomada eggs hatch into larvae, they eat the pollen that has been carefully provided for the mining bee larvae. Very cheeky! 

N.B. some of these nests may belong to solitary wasp species. Neither the solitary wasps, nor the solitary bees are likely to sting you.

For more information about ground nesting solitary bees and the importance of short grass and bare soil for habitat, do please watch this little video of an interview I did with Stuart Roberts, chairman of BWARS (Bees , Wasps & Ants Recording Society)  

Importance of short grass for ground nesting solitary bees

Tuesday 10 March 2015

Hairy Footed Flower Bees & Silver Linings

I've been feeling extremely frustrated. Winter is over, spring has sprung, the sun is shining, the pulmonaria is flowering, and everyone I know is reporting sightings of Hairy Footed Flower Bees. Actually that's a slight exaggeration - only some of the people I know are reporting sightings of Hairy Footed Flower bees.

But that's not the point. The point is that whilst all this wonderfulness and excitement has been going on outside, I've been stuck in bed with an extremely unpleasant lurgi. Fortunately I'm beginning to recover now, but whatever it was has left me feeling so weak & weedy that I can't get dressed, let alone drag myself downstairs to go for a walk.

Every cloud has its silver lining though, and my silver lining is that I have just written a large chunk of the opening chapter to my book!

I started writing a book a couple of years ago, but lost everything I'd written (and a lot more besides) when the hard drive on my laptop died and I wasn't able to retrieve the contents. It has taken me till this morning to find the momentum to start again from scratch.

I'm going to resist the temptation to copy my opening paragraphs into this post. Suffice to say my book has bees in it and it starts with a fluke sighting on 17th February of a female Hairy Footed Flower bee who emerged far too early from hibernation….

So, thank you universe for laying me up with a horrible lurgi. I'm HUGELY excited by this silver lining!