Wednesday, 29 August 2012

The Bee & Bee in your garden or how to help solitary bees


Solitary bees are important pollinators but often overlooked in favour of the bigger and more obvious bumblebees and honeybees. We thus thought it can’t do any harm to bring them into the spotlight here on our urban pollinator blog.
There are more than 200 species of solitary bees and you can see them buzzing around in your garden as early as March. Solitary bees do not live in large colonies and do not have any worker bees (with a few exceptions). Each female solitary bee is fertile and inhabits a nest built by herself. There are two different types of nests; ground nests build by sweat bees, (Halictids) and alkali bees (Andrenids) and cavity nests build in hollow reeds, twigs or holes in wood by leafcutter bees and orchard bees (e.g. genus Osmia).

Andrena fulva, a ground-nesting solitary bee

Each female constructs a series of cells, each with a food source (pollen and nectar packed into a ball) and a single egg that is laid on top. The nectar and pollen for each cell is gathered in several foraging trips, and this is why solitaries are such useful pollinators. Depending on the species, the cells are lined with various materials, including leaves, petals, mud or body secretion. When the entire nest is complete it is sealed off and the next nest started.

Depending on the species, solitary bees have one to several generations a year. In species with just one generation per year, it is usually the pupae or larvae that overwinter in the nest and emerge in spring the next year. The first bees to emerge are normally the males. They will often wait near flowers to mate with the emerging females. The males will then die and the females will search for nesting places.

A little Red mason bee male emerging from a nest

If you want to learn more about different solitary bees have a look at our other blog posts about the   Hairy-footed flower bee (Anthropora plumipes), the Tawny mining-bee (Andrena fulva), the Red mason bee (Osmis bicornis), the Harebell carpenter bee (Chelostoma campanularum) and the Ivy bee (Colletes hederae).

A female Hairy-footed flower bee visits Pulmonaria flowers

A shed is a good place for solitary bee "hotels"
If you want to help solitary bees you can provide nesting places in your garden. Ground nesting bees normally find their own nesting sites in loose and often sandy soil in sunny places with short grass. But you can really help the cavity nesting bees if you provide them with hollow reeds, canes or twigs stuffed tight in a wooden box, tube or tin or with wooden blocks with holes drilled into them (try to drill holes with different diameters, ranging from 2 mm to 10 mm). You can also cut bamboo canes of different sizes in pieces, bundle them together and hang them up (make sure you cut them before a join so they are closed at the back).

Soon the first solitary bees will arrive to nest in your "bee hotel"

Of course you can also buy a commercially available bee hotel but make sure you buy one with holes with different diameters to attract a range of different bee species.

Mason bees like bee hotels attached to south-facing house walls
It is very important to hang the bee hotel somewhere warm and sheltered about 1-2 m above the ground, a south facing wall is often ideal. And don’t be afraid of hanging the bee hotel close to your door or window as solitary bees do not sting.

Solitary bees tend to forage in the vicinity of their nest. If you don`t have already lots of bee friendly flowers in your garden or allotment you can further encourage them by planting these. To find out which plants are considered bee friendly, just visit a plant nursery or garden center on a sunny day and buy the plants which are most visited by bees and other pollinators. Also have a look here and here for more ideas of what to plant.

Plant lots of flowers for your solitary bees

Below you can see some examples of bee hotels we found in the gardens we have sampled for pollinators.

A bee palace, but try to put it in a location as sunny as possible
If you add more holes you will attract even more bees
A bee hotel made from a wooden block with holes drilled in.
A bee hotel with enough space to accommodate other insects as well

12 comments:

  1. I commend you for writing this post! I'd like to help you think through one change. Although holes in wood is natural, through pest buildup, we wind up losing most of the nesting bees over time.

    Rather, we should be encouraging gardeners to harvest their cocoons in the fall. They can then spread the bees to other gardeners. This will bring out much more native bees! I will follow you on twitter.

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  2. I have not heard so far that pests or diseases are a major concern for solitary bees, this is more the case for the honeybee. Solitary bees have more problems I think with finding suitable nesting places and finding enough food (nectar and pollen-rich flowers) through the season.
    If we provide more nesting places and pollinator friendly flowers in our gardens we can really help the solitary bees.

    I don`t really know what you mean with moving the cocoons around but once the bees have build their nests they (the nests) should not be moved around as the bees know exactly what the right place for the development of the eggs and larvae is and if the nests are moved around they could end up in an unsuitable location.
    Also the adult bees are mobile so will fly from garden to garden them self so they don`t have to be moved around.

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  3. HI,
    I am writing you to ask if i have your permission to use the picture of the "solitary bee emerging from nest bundle" on my pollinator conservation page.
    It would appear on this page should you give your permission

    http://gapp.org/building-your-pollinator-garden/introducing-new-habitat-elements/

    ReplyDelete
    Replies
    1. You can use the picture if you mention that the picture was taken by me (Urban Pollinators Project: N Mitschunas), that is no problem.
      More mason bee pictures you can find here (if you have not seen them already): http://urbanpollinators.blogspot.co.uk/2013/05/the-secret-life-of-red-mason-bee.html

      Delete
  4. Hi,
    I am commenting to ask if I can use the " Solitary bee emerging from a nest in a hollow reed" picture for a poster for an undergraduate poster presentation. My poster is about cavity nesting bees.

    Thank you

    ReplyDelete
    Replies
    1. No problem to use the picture if you mention somewhere that the picture was taken by me (N. Mitschunas).
      Hope your poster presentation goes well.

      Delete
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  6. I 100% agree with Dave Hunter and its great to see you showing examples of different solitary bee nest boxes at this time of the year.....they make excellent xmas presents!

    Researchers have found pollen mites to be a serious pest of some UK solitary bees. They 'infect' wood borings used as bees nests and some solitary wasps, e.g monodontomerus are another huge problem. Species of chalkbrood also kill solitary bees.

    I have managed my solitary bees for over 20 years and greatly increased their numbers, based upon my own observations, nest designs and managing cocoons. Although the nest boxes you show look good, even grand! I can see at a glance that many holes will not be used, they offer great opportunities for pests to multiply and kill the bees and also great places for pests to hide. They can easily be death traps. Little thought has gone into their design..... There are better example now out there which go some way to addressing the problems I outlined. I believe in nurturing nature and that includes bees! Keep up the good work, I look forward to these postings! George Pilkington

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  9. Hi
    Could someone advise me as to how to move an underground bee nest without harming them?
    I'm due to have a patio installed and have noticed a small orange furry bee, some sort of solitary mining bee I guess, going into a small hole in the earth.
    I'm worried that this is a very bad time of year to disturb the nest.
    Is it possible to dig a large cube containing the nest out and re-site it? If so, how big is the nest likely to be?
    Any advice would be appreciated.

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