There
are few things more uplifting than the sight of a bright
yellow brimstone butterfly winging its way across the garden
on the first sunny day of spring, or a red admiral in the late
summer, feeding on Buddleia or sunning itself on a sheltered
leaf. But my favourite butterflies are the family of blues,
with wings that shine like little jewels as they flash past or
sit in the sunshine on a blade of long grass. You are most
likely to see the first common blues in gardens in late May, whereas
earlier in the year, the holly blue is more apparent. This
family of butterflies technically includes the hairstreaks and
coppers and many people find them very confusing, especially
as amongst the blue species the females may be brown.
However, with a bit of help from a good identification guide
there are ways of recognising these beautiful insects and by
growing the right plants for them, some species can even be
encouraged to your garden.
There
are eight species of blue butterfly in this country but rather
few find our gardens amenable, due to their complicated life
cycles and adaptation to specialised habitats. Some species
need ant colonies to be present in the soil, and the
caterpillars have a highly specialised association with these
creatures. The common blue however is quite an adaptable
butterfly and relatively easy to entice to your garden if you
have some meadow grass and its main larval (caterpillar) food
plant – the lovely bird’s foot trefoil. The male common blue
has bright blue upper sides to the wings, edged by a thin
black line and a white margin. His female counterpart however
is usually dull brown, or brown with blue suffused through the
upper wings and she has small orange spots around the wing
margins. Both male and female are beautiful insects, their
under wings being silvery grey with black centred white
spots. The female also has orange markings, known as lunules,
on the undersides of her wings - these are highly visible when the
insects are feeding on flowers with their wings closed or
‘roosting’, usually upside down on grass stems, in the evening. The
common blue usually has two broods a year, and after mating in
June, eggs are laid on the leaves of bird’s foot trefoil or
black medick. The tiny caterpillars are green and rather slug
shaped, and they eat their way through the leaves until they
are ready to pupate. The pupa stays at ground level and
hatches at the end of July to produce the new brood of late
summer adult butterflies. These mate and lay their eggs, but
the tiny caterpillars feed only for a short while and then
spend the winter months deep at the base of grasses and other
vegetation until the spring, when they start to feed again,
before pupating and hatching the following June. The
other blue butterfly commonly seen in our gardens, especially
older country or suburban plots, is the holly blue. If you
find the blues confusing to identify, timing here is useful.
Any blue butterfly in your garden in April or early May is
likely to be a holly blue. This strong flying little
butterfly is found only in the south of the country and is
most likely to be seen in your garden if you have holly and
ivy, its two larval food plants, nearby. It is a species that
has good and bad years in terms of its numbers, and this
natural cycle is thought to come about as a result of the
presence of a parasitic wasp, which preys on the holly blue
caterpillars. There are two broods each year, and the first
holly blues are generally seen in April. These mate and lay
their eggs on the tiny developing flowers of holly or
occasionally the native shrub dogwood, which the caterpillars
then eat. After pupation a second brood appears in July and
August. These adults lay their eggs on the flowers of mature
ivy and the tiny bright blue butterflies can sometimes be seen
flying high up around the tops of walls where the ivy flowers
are situated. The caterpillars that result from this brood
pupate and spend the winter in this state, ready to emerge in
the spring sunshine. Holly blues take nectar from rather
limited sources, but marjoram and forget-me-not are useful, as
are the flowers of ivy. Holly blue can be confused with the
common blue, but unlike that species has fewer markings on the
undersides of the wings, which are pale blue with small black
spots. The females also have a dark margin to their wings. Some
gardens in the south may have the occasional brown argus
butterfly. Another member of the blue family, this tiny
butterfly looks remarkably like the brown form of the female
common blue, and I find it extremely difficult to tell them
apart. Brown argus generally lay their eggs on the wild
rockrose, but in my previous garden chose the small
dove’s foot cranesbill as an alternative larval food plant.
This butterfly also takes its nectar from wild marjoram, a
must-have plant in any butterfly garden. Another member of
this family is the small copper, a stunning little bright
orange butterfly that lays its eggs on sorrel. Again wild
marjoram will tempt it to feed as will water mint on a pond
margin.
A few
years ago a group of refugees from Eastern Europe – all keen
gardeners - visited my wildlife garden in Oxfordshire. Whilst acknowledging
the value of gardening for all manner of reasons, and
delighting in my vegetable patch, they could see no reason
what so ever to garden for wildlife. ‘What use’ they asked
‘are butterflies’ looking at the wildflower meadow areas?
Surely the garden could have been put to better use if more
food was grown there? A valid question, and to justify my
passion for wildlife gardening, after some rapid thinking, I
replied that butterflies were good for the soul, and my
comment was met with some thoughtful nods and murmurs of
understanding. For me this group of delicate, colourful
butterflies makes wildlife gardening worth all the effort.
Attracting the Common
Blue. This species is the easiest of the blue butterflies to attract to
gardens, and you can encourage them by dedicating a small area
of the garden especially to them. Choose
a sunny spot either to sow a small area of native meadow
grasses, or allow an area of fine lawn (not rye grass) to
remain uncut through the summer months. Using a trowel or bulb
planter, remove small areas of turf and add small plants of
bird’s foot trefoil in either spring or autumn. These can
easily be grown from seed in a peat free compost and pricked
out into small pots when they are large enough to handle. The
area should be allowed to grow up uncut from March until
September – the male blues love the long grass for sunning
themselves during the daytime and for roosting in the
evenings. After cutting to a height of 5 to 10 centimetres in
September, carefully rake off the cut grass with a spring
rake, taking care not to trample about unduly – remember that
those tiny caterpillars could be down at soil level where they
will remain until the following spring. Leave the area
completely undisturbed throughout the winter. A few of the
adults’ favourite nectar plants including cornflower and wild
marjoram somewhere near by, will also help to establish a
colony of this beautiful butterfly in your garden.
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