In
these days of increasing awareness of the benefits of organic
gardening and farming, biological control is big business.
Introducing beneficial insects into our gardens or greenhouses
is now a fairly normal approach to pest control andr
pollination, and in certain situations can be a very effective
way of dealing with unwanted insects such as whitefly or
aiding the setting of tomatoes. But however useful this
scientific approach may be, many gardeners would still prefer
to encourage useful creatures using natural methods, building
up a well balanced garden over time, rather than introduce
predators in unnatural quantities or bumblebees into areas
where natural pollinators are lacking. If we can encourage
these insects to colonise our gardens naturally there is more
likelihood that the environment will be right for them and
their populations will increase.
As far as pollinators are
concerned there are over 260 different species of bee in the
UK, but at least a quarter of these are in serious
decline, mainly due to lack of wildflowers in meadowland and
hedgerows on which they forage for pollen and nectar.
Bumblebees, solitary bees and honey bees all need a good
supply of these plant foods, for themselves and their larvae,
and the all important pollination occurs as they move from
flower to flower. It therefore stands to reason that a good
supply of nectar and pollen producing plants is a first step
towards establishing plenty of pollinators of all types.
Most of us know something
about honeybees and bumblebees but solitary bees
are a particularly useful group of insects and it is not
difficult to cater for their needs in any garden. Many
species occur in small numbers in gardens and on allotments,
and populations of these useful insects can be encouraged to
increase by providing the food and conditions they require.
Many of the solitary bee species
will nest in artificial homes. Red and blue mason and leaf
cutter bees in particular are easy to cater for, and nest
homes can be made for them quite easily by using a few things
readily found in the home or garden, ranging from off-cuts of
softwood and hollow plant stems to empty baked bean tins! To
make a simple bee nest home, completely remove the lid of a
tin can and wash the tin thoroughly with care. After drying, paint the
inside end with a waterproof adhesive and pack the tin tightly
with large diameter paper (not plastic) 'art' straws, each one about
a centimetre shorter than the tin. The completed home should
be painted on the outside to prevent rusting, and then
attached with string or tape to a south facing, bee friendly
spot such as under the eaves of a wooden garden shed. It is
usually recommended that these homes are sited at about chest
height, but I have effectively used them beneath a sunny
downstairs windowsill. A south facing woodpile in the garden
is also the sort of place that female bees may be house
hunting. This type of home can be packed with sections of
hollow bamboo cane or plant stems as an alternative to
straws. I prefer plant stems from species such as hogweed or
sweet cicely, which are cut to size in the late winter and
left to dry in a sunny shed or greenhouse. The natural
variation in the diameter of the stems will encourage a range
of bees, rather than one species. If you prefer a completely
natural looking home, a triangular or square box made with wood off-cuts
and a plywood back works very effectively.
An alternative home can be
made by drilling a series of holes in a 5cm square piece of
softwood, about 15cm in length. Use the longest drill bits
you can find, and make holes between 7 and 10mm in diameter.
This can be placed in a pile of logs or attached to a fence or
shed, again south facing. If you would rather buy a superior
bee home, there are now several available from garden centres
and mail order catalogues. The Oxford Bee Company has
pioneered this work and has a selection of insect homes
specifically for red mason, blue mason or a combination of the
two. As the red mason is a slightly larger insect she
requires tubes of a larger diameter.
The female red mason bee,
recognisable from the fuzz of gingery-red hairs on her body,
will be seeking a nest site in March and April. After mating,
each solitary female will lay single eggs inside the tubular
holes, sealing each one into its chamber with a quantity of
pollen for the larvae to feed on. The ends of the chambers
are sealed with mud, which she carries to the nest in her
jaws. The blue mason bee seals her nest chambers with a glue
made of chewed leaves. Later in the year the leaf cutters
(species of Megachile) will use vacant holes in the same nest
home, filling the ends with circular sections of leaves
carefully cut from roses, willow herb and other common
plant species.
The life cycle of these
useful insects is fascinating and complex. The young
bees remain inside their chambers until the following spring
when they hatch and begin the job of pollinating your garden
fruit, flowers and vegetables with great efficiency.
Actively encouraging them to your garden or allotment and
building up a population by providing them with breeding homes
and food will ensure that your fruit and vegetables set in the
natural way that nature intended.
If you prefer to buy homes
for solitary bees in your garden look out for those that are
specifically for red mason bees. Many of the 'insect
habitats' now common in Garden Centres are almost useless.
You can also grow a selection of bee
plants to encourage as many species of bee as possible to your
garden. Here are some of the best:
Herbs especially rosemary,
lavender, borage, hyssop, mint, thyme and marjoram
Annuals and biennials
including wallflowers, poached egg plant, mignonette, bugloss and phacelia
Perennials especially
cranesbills, dead nettles, fleabane and globe thistle
Wildflowers especially
knapweed, vipers bugloss, clover, scabious, vetches and
trefoils
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