If
bumblebees hadn’t been invented I have no doubt there would
now be a mythical version – the cute and cuddly equivalent of
a dragon or the fairies that as children we imagined were at
the bottom of our gardens. What could be nicer than a round
furry flying creature with a gentle droning buzz, a striped
coat and a docile nature? Perhaps we would omit the sting
(and anyone who has been stung by a bumblebee will know that
it is every bit as painful as a honeybee’s) but other than
that the bumblebee for me is the perfect insect, and I forgive
it the occasional act of self defence.
Gardens can be wonderful habitats for bumblebees and are well
used by these insects when the conditions and the plants are
right for them. It is now well documented that around half of
our 24 species are declining rapidly in the wild and one has
probably become extinct in recent years. Sadly good nesting
sites and suitable nectar and pollen producing plants are in
ever-shorter supply in the countryside, plus the widespread
use of insecticides in farmland has taken its toll of
bumblebee numbers. Our gardens have become important refuges
for these insects but we need to take positive steps to ensure
that numbers increase. With some garden wildlife it can be
enough to do very little except create areas where creatures
can go about their business undisturbed. With bumblebees we
have to be a little more proactive in our planting plus it is
possible to create areas where they can build their nests once
we know more about their life cycles.
Apart
from the aesthetic reasons for encouraging these insects (and
what garden doesn’t look better for being full of life?)
bumblebees are beneficial to the grower. They are essential
for the pollination of certain crops, both commercially and in
our gardens. Bumblebees are of great economic importance,
pollinating a wide range of food crops including tomatoes,
beans, peppers, aubergines, kiwi fruits, soft fruits such as
raspberries and strawberries, plus apples and plums.
Commercial tomato growers introduce these insects to
glasshouses and poly-tunnels where their unique form of
pollination – vibrating their wing muscles at a specific speed
to encourage the tomato flowers to release their pollen –
provides a very efficient means of setting fruit. Any
allotment holder knows the value of having plenty of
bumblebees around and with the alarming decline of honeybees
due to a range of causes, we need to
take greater care of these natural pollinators.
Like
all garden wildlife bumblebees need a few specific
requirements to flourish and thrive. Food in the form of both
nectar and pollen is essential and a place to nest and
reproduce is vital. Both of these requirements can be met by
the determined and interested wildlife gardener although the
former is rather easier than the latter! Bumblebees are
notoriously difficult to tempt into artificial nests, but with
a little thought there are plenty of things we can do to make
potentially attractive natural nest areas for them. In order
to do this well is it useful to know a little about the
bumblebee life cycle.
In May
we should be seeing plenty of bumblebees around our gardens.
These will be new workers that have recently hatched from
nests created by a queen bumblebee earlier in the spring.
In the autumn months the queen could have been around in your
garden searching for a suitable underground place to hibernate
for the winter months, not emerging until spring. Having
mated in the late summer she might use a hole she found, or
excavated an underground cavity herself. Here she will
stay right through the winter months until the warmth of the
spring sunshine in March or April wakened her. After
emerging from her chamber she begins to search for food – she
needs both pollen and nectar to build up her fat reserves.
Her next task will be to find a suitable breeding nest site.
Queen bumblebees are often seen in the spring zigzagging
across the ground searching for somewhere to lay eggs.
She will be especially seeking an old vole or mouse nest which
she can detect by its smell, but the proximity of a good
foraging area with plenty of nectar and pollen producing
flowers will also influence her choice. She needs to
make sure that there will be available food for her offspring
not too far away. If a old nest is not found she will
build her own in a hole in a bank or in dead vegetation but
the location will vary with species. The carder bees are
a type of bumblebee that will tease out and pull together
mosses and dried grasses to make their nest (hence their name
– carding being the process of combing wool before spinning)
so are more likely to be found in compost heaps. Other
species will chose a hole in mossy or grassy bank, or
occasionally a disused birds nest, even if it is in a nest
box.
When
the nest is ready the queen will collect pollen which she
forms into a mass and onto which she deposits her eggs. Once the
eggs have hatched she tends the larvae with great care,
keeping them warm with her own body. They grow and eventually
pupate, emerging as smaller versions of their mother in a few
weeks. The queen continues to lay eggs and the new worker
bees collect food as the colony size increases. It is not
until the summer that male bees are produced together with new
queens. These mate, the males die (as do the workers and the
old queen) leaving only the new young queens to find a home,
survive the winter and begin the cycle again.
As
gardeners we can help these useful bees during their short
lives. Ensuring that they have a good selection of plants to
provide the nectar and pollen they need is relatively easy.
Some of our most attractive cottage garden plants will attract
bumblebees and it is no hardship to include a good selection
of these in our gardens. Foxgloves, hardy geraniums,
verbascum, antirrhinums, campanulas, lavender and poppies are all
excellent bumblebee plants. They also love the flowers of
buddleia (especially Buddleia globosa) and many other shrubs
including hebe, pussy willow and ceanothus. A wildflower
meadow will hum with bees if it contains knapweed, clover,
bird’s foot trefoil and field scabious. Other useful
wildflowers are the woundworts, mints and many other members of
the Labiate family, plus thistles, comfrey, vipers bugloss and
heather.
Helping your bumblebees to nest is another matter. Many types
of bumblebee nest home are available, but unlike the solitary
bees which will readily use artificial nest homes, I have
never managed to encourage bumblebees to use these nest boxes,
or for that matter heard first hand of anyone who has.
However I have had plenty of nests in my gardens especially
where grass, left to grow long, has encouraged small mammals.
Their redundant nests have been used readily by bumblebees in
many situations. In my previous dry garden they would take
over any empty nests especially on the edges of meadows or
areas of undisturbed grass beneath hedgerows. In my current
wetter garden mammal nests on well-drained banks and slopes
have been used, which seems to make sense as the flatter areas
are more easily waterlogged in wet conditions.
Wildflower meadows are especially good habitats for these bees
as they provide both nest sites and food plants, so if you do
want to encourage more bumblebees to pollinate your fruit, vegetables
and flowers create a bumblebee meadow with a good selection of
wildflowers known to be attractive to these useful insects.
This can be done in a variety of ways but even an area of long
grass, a corner of a lawn left to grow or grass running up to
or beneath a hedge could be sufficient. Although bumblebees
will forage for up to half a mile for pollen and nectar, the
close proximity of a border with a good selection of flowers
including labiates, daisies, globe thistles, poppies and
foxgloves will influence the choice of nest site. Further
inducement to nest could be to create holes in bank and push
into each one a loose bundle of moss about the size of a
tennis ball. A sheet of corrugated tin laid on the ground in
an out of the way place might also tempt a carder bee queen to
create a nest beneath it.
When
gardening for wildlife it is important to provide natural food
for your garden visitors throughout the period when they may
be around. This is especially true of the bumblebee – the
queen in particular needs pollen and nectar when she emerges
in the spring. Her survival at this time is paramount so make
sure you have plenty of dead nettles, lungwort and bugle,
berberis, flowering currant and pussy willow in the spring.
Lastly leave dandelions wherever you can and she could well
reward you with a nest of young bees ready to pollinate your
fruit and vegetables. |
