The Leafcutter Diaries 2 – 8th July

I’d seen ‘our’ Leafcutter roosting in the beehouses for a few weeks now, but tonight was very happy to see that she’s started nesting there!  As I went out into the garden after work one night I saw her going to and from the beehouse, returning each time clasping a section of leaf before taking it into the tunnel.

I grow a rose bush in the garden especially for Leafcutter bee nesting material – I’d read that rose leaves are their preferred choice when constructing nests.  I’d been watching this carefully to spot any signs that it was being used with no joy, and each trip the bee made to fetch leaves was very short – with only a minute or so between her leaving the beehouse and returning.  So where was she going?

It didn’t take me long to find the answer.  About 6 feet away from the beehouses is a Snowberry bush, and this showed the tell-tale signs that a Leafcutter bee had been at work.

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That night I also managed to get a shot of our Leafcutter bee-hind, which meant that from this and her size I could finally identify her as a Wood-Carving Leafcutter Bee (Megachile ligniseca)

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I staked out the beehouse over the weekend and managed to get a shot of her bringing a leaf back to the nest.

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I thought she must be getting close to finishing this nest as she seemed to be ‘auditioning’ new tunnels in between completing the current one, flying around the front of the house to view all the options and popping in and out of tunnels for a closer look.

Then by the end of the weekend, she’d finished!  Leafcutters always seem to like to finish a nest off by sticking a full leaf to the front for a final flourish.

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Leafcutter Diaries 1 – 21st June 2017

Every evening when I get home from work one of the first things I do is head on out into the garden.  I love to potter around for 5 minutes of so, filling the bird feeders and checking out what’s been going on – it gives me some much needed reprieve after a long day at work and busy commute.

Today as soon as I opened the door I could hear a strange crunching noise coming from the bottom of the garden.  I headed down there and found the source of the noise at the beehouses.  One of the houses I made this year was a bit of an experiment and uses dry plant oasis as the nesting material.  It was this house the sound was coming from.  I made myself comfortable and waited.

As it happens I didn’t have to wait long before the culprit emerged – a Leafcutter bee!  She was entering each hole and chewing them to make them precisely the right size for her.  Every couple of minutes she’d back out of the hole, pushing the ‘spoil’ out behind her as she went.  I ran for my camera and managed to get a couple of shots but the combination of the dull evening light and her frantic activity meant that these weren’t the best.  All the same, I wanted to record this.  We’d had Leafcutter bees in the garden before foraging, mainly the smaller Patchwork Leafcutter bee (Megachile centuncularis), but this was the first time I’d ever seen one near the beehouses.

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This Leafcutter seemed larger than the normal foragers though.  I knew there wasn’t much possibility of being able to ID her (she had to be female as the chewing is nesting behaviour) due to the amount of oasis she had stuck to her body.  I’d just have to hope she found the accommodation on offer acceptable and decided to stick around!

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A Day at the Seaside

A conversation with a fellow bee fan on Twitter led us to Ainsdale Beach on the hot and sunny Easter weekend.  Ainsdale Beach is part of the Sefton Dunes NNR (National Nature Reserve) and is designated as a Special Area of Conservation – not just due to the wildlife found there but also due to the fact that is is part of the UK’s fastest-eroding section of coast.

It is a shifting dune system and therefore needs to be carefully managed as the form and shape of the dunes constantly changes.  There are large areas of the dune system which flood seasonally and provide a habitat for many coastal species.  It is host to a number of uncommon and rare species such as Natterjack Toads and Sand Lizards as well as the smaller creatures that I had come to see.

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I was looking for the Vernal (or Spring) Colletes, a fairly uncommon bee that is only found in the UK at a few sites on the North West Coast and North Wales.

The Vernal Colletes nests within the sand dunes, using the hollowed out surfaces on the side of the slacks caused by erosion.  South facing slopes are preferred for maximum sun exposure to keep the nesting area as warm as possible.

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The bees form large nesting aggregationss, containing thousands of nest tunnels and bees.  Although Vernal Colletes are a species of Solitary Bee, they could perhaps be described as ‘Semi-Social’ as although they nest individually the tunnels are formed in close proximity to others.

As we approached the nesting area the hum caused by the buzzing of flying bees was incredible.  Hundreds of males were flying just above ground level in search of females.  Occasionally one would dive-bomb another male in a case of mistaken identity, at which point a small scuffle would ensue until the mistake was realised!

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The females mostly hid within their nest tunnels, waiting until the coast seemed clear before emerging.  I spotted a few peering out, the slightest movement meant that they bobbed straight back down again so they were quite a challenge to photograph!

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I staked out one nest tunnel for a while, and only once the female within was happy that I was not a male bee did she finally emerge!

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Any female spotted by males out in the open was quickly mobbed, though we did manage to spot a brave few digging new nest tunnels.

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There was only a small population of Vernal Colletes at this site a generation ago, but a few changes to the management of the dunes has meant that the population has increased dramatically over the past few years.  Parts of the dune system have been fenced off to protect the Natterjack Toad breeding pools, which means that Vernal Colletes nesting on the steep poolsides were protected from disturbance and damage caused by footfall, which they are particularly susceptible to.  Secondly, Salix repens (or Creeping Willow) which is the Vernal Colletes exclusive food source was encouraged which in turn has meant a larger population of bees is able to be supported.

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After a couple of hours taking pictures it was time to head for home.  We walked back to the car park through the dune system, seeing many more nesting aggregations en route.  We also spotted several of these pretty Northern Dune Tiger Beetles scurrying through the sand.

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It was only when we reached the very top of the dunes and were immediately sand blasted by the wind that I realised how sheltered the dune slacks are – where we’d been had been hot and completely still – and so why they make such a great habitat for so many creatures.

Solitary Bees

When you think of bees, you probably think of two different kinds – I know I used to!  The big fat fuzzy ones – Bumblebees, and the skinnier ones which look similar in shape to wasps – Honeybees.

It wasn’t until a couple of years ago that I realised that there seemed to be other bees visiting the flowers in the garden.  I knew they weren’t Honeybees – I’ve been a beekeeper for 5 years so that’s one species I can comfortably identify!  And they were way too small for Bumblebees – so what were they?

A little research told me that they were solitary bees.  And to my surprise, my reading told me that there are about 270 different species of bee in the UK, and around 250 of those are solitary bee species.  So Honeybees and Bumblebees are actually the minority.

Honeybees and Bumblebees are social bees – they live together in a colony comprising of workers (females), males and a queen.  Solitary bees, as the name suggests, live alone, though they can sometimes nest in close proximity to others of their own species, giving the impression that they are part of a large colony – as seen in the photo below.  This is a large group of nest tunnels used by Mining Bees.

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Mining Bee Nest Aggregation – September 2016

While in social bee colonies young bees are born and raised by their siblings and live as part of a community headed up by a Queen, Solitary Bees go it alone from day one. During the chill of Autumn and Winter, an egg is forming into a baby bee.  It was laid the Summer before in a nest chamber by a mother bee who will never meet her offspring, and sealed in with a stockpile of pollen left as food.  It will become a larvae, then slowly undergo the metamorphosis needed to turn into a bee.  One Spring day it will hatch out – and spend the Summer following repeating the cycle, and so laying the foundations for the next generation of it’s species.

While this aspect of the lifecycle are common to most species of Solitary Bee, in most other ways they are a staggeringly diverse group of species in terms of their appearance, living conditions and behaviour.  Some nest aerially, in holes in wood or plant stems, others choose to site their nest underground or even in old snail shells!  Nesting chambers can be sealed with mud, leaves, plant fibres or resin.  They will collect pollen and nectar from almost any plant or from a single species.  This they will carry on their legs, on their abdomen or some will ingest it as they lack any apparatus to store the pollen they collect externally.  They can range in size from a few mm long to 15mm.  They can be all black or red and black, be yellow and black like social bees, and seemingly any colour inbetween.  Some species are a metallic green or bronze, and some have beautifully multicoloured eyes.  Most only fly for a few weeks, but the different species flight seasons are spread across the year so there are usually Solitary Bees on the wing from March to November.

There are even ‘cuckoo bees’, who (and the clue’s in the name here) don’t fashion their own nests but lay their own eggs inside nest chambers carefully prepared by an unsuspecting mother bee for her own offspring.  Different species of Cuckoo Bee will parasitize each species of Solitary Bee, to ensure that the larvae will develop at a similar rate and that the pollen stores in the host bee nest chamber are suitable for the cuckoo.

The more I read, the more I wanted to know!  Before I knew it, I’d fallen head over heels for the tiny creatures, and I’ve tried to focus a lot of my efforts in developing the garden on making a suitable environment for them.  Here I’ll cover some of the species of Solitary Bee that I’ve come across over the past 18 months in my garden and elsewhere.

Mining Bees

Mining Bees (species Andrena) are one of the first species of Solitary Bee to emerge in the Spring and the last to fly in the Autumn with some species emerging in March and the Ivy Bee in September.   As the name suggests they nest in the ground, and a suitable spot will often see many nest tunnels in use, giving the impression that the bees are in a colony.  I was lucky enough to see this male hatching from his nest tunnel on the bank of a lake in a local nature reserve.  The entrance to his tunnel had actually been partially blocked by a large stone which we carefully removed to help him emerge from his nest tunnel for the first time.

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Unidentified Mining Bee – March 2016

Different species of Mining Bees nest in different environments, from bare soil to lawns to golf courses to sand dunes.  They collect pollen on their legs, a build up of which can make them look like they are wearing pollen pants –

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Grey-Banded Mining Bee, Andrena denticulata – July 2016

Mason Bees

Mason Bees (Osmia species) nest in various places, such as holes in wood, plant stems and old snail shells.  They can often be seen in garden bee hotels, where they plug up holes with mud, behind each cap will be several chambers containing developing bees.

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Mason Bee Mud Cappings in Bee Hotel – 2016

These cappings were made by a Red Mason Bee, we’ve had these large bees in the garden for the past couple of years but this is the first year that we’ve had more than one chamber in the bee house filled – I’m hoping this means we have lots more next year.  These are normally one of the first Solitary Bees that I see in the garden and that’s when I know that Summer is on the way!

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Red Mason Bee – Osmia bicornis – May 2016

This year we’ve also had Blue Mason Bees, the females of which are dark, glittery blue. The males are really striking – a bronze and gold colour with multi coloured eyes.  They seem to enjoy sunbathing on the roof of the bee hotels on Sunny days.

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Blue Mason Bee, Osmia caerulescens – May 2016

Mason Bees are remarkably efficient pollinators, and are said to be more effective than Honeybees or Bumblebees especially for fruit trees. Their value as pollinators is now being recognised and they are sometimes used for commercial pollination in orchards.

Furrow Bees

Species Lasioglossum and Halictus, these are small bees that most often nest in the ground.  They collect pollen on the legs or abdomen.  Males are easily identifiable due to their long antennae and slender abdomens.  They are also called ‘Sweat Bees’ as they are said to be attracted to sweat.  They seem to be attracted to a range of different flowers but they adore Ragwort – we have a clump in the garden and if I wait by it on a sunny day in the Summer it won’t be long before a Furrow Bee turns up.

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Male Furrow Bee – July 2016
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Female Furrow Bee – July 2016

Leafcutter Bees

Species Megachile, these bees cut small holes out of the edges of leaves to seal off their nest chambers using their fearsome looking mandibles.

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Leafcutter Bee – June 2016

If you notice crescent shaped holes in the edges of the leaves on rose bushes, Leafcutter Bees are probably the culprit!  They fly to the nest site with pieces of leaf which they will cut up further and mix with saliva to make a sticky paste to seal the entrance with.

They collect pollen on their abdomen which then takes on the colour of the pollen they have collected as seen here.

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Leafcutter Bee – July 2016

Leafcutter Bees often nest in holes in wood, and so are the other species often seen in garden bee hotels.  I often see them collecting pollen in the garden, but have not known them to nest here yet.  I planted a rose bush this year in the hope that ready access to both pollen and nesting materials would tempt them to stick around!  We’ll see how well this works next summer.

Yellow Faced Bees

Hylaeus species, these tiny black bees take their name from the yellow or white markings on their faces.  They move like lightning and seem quite shy – other species don’t seem to mind me sticking a camera in their faces, these – not so much.

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Yellow Faced Bee – July 2016

Yellow Faced Bees collect pollen and nectar in an unusual way – they lack any apparatus to store this on their outsides, so collect it in their crop – a muscular pouch near their gullet used to store food temporarily.

I found this one standing uncharacteristically still one day last year, and I noticed that it seemed to be ‘blowing a bubble’.  It is regurgitating the pollen/nectar mix that it has collected – the sun warms the bubble and concentrates the mixture.  Quite a unique space saving technique – IKEA eat your heart out!

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Forever blowing bubbles…

I’ll write in more depth about some of these bees in further posts, and the things I’ve done to try to encourage them to call the garden ‘home’.