June
is wonderful month in the garden – full of the promise of
summer but still with the green lushness of spring. In the
countryside and the wildlife garden, the breeding activity of
birds and small mammals may be coming to an end but many of
our butterfly species are still in the throws of mating and
laying eggs. If your garden is butterfly friendly with plenty
of nectar and larval food plants to attract these insects, you
could see a good variety of species early this month
especially the spring butterflies such as orange tip and
brimstone, together with the first of the summer butterflies,
including common blue and small copper.
Our
native butterflies have varying strategies to help them
through the winter months. The brimstone hibernates as an
adult insect deep in vegetation, ready to fly as soon as the
sun shines in March or sometimes February. Small tortoiseshell,
another of the early fliers, over-winters in garages and sheds
or under loose bark on fence posts or logs. Others species,
such as the large and small whites, spend the winter as pupae,
safe from the worst of the weather, and the common blue
survives the cold conditions as a tiny caterpillar sheltering
deep in ground level vegetation. The whites will emerge as
fully-fledged adults in April or May while the common blue
larva will complete its transformation in May or early June.
However, other butterfly species that appear in our gardens
this month have not spent the winter here at all, and reach us
in late spring having flown across the Continent, an
extraordinary fact that many people find quite amazing. We
are used to the idea that birds migrate between countries,
often over vast distances, but few of us appreciate that
insects also perform these feats of endurance – especially
butterflies and moths. Our winters are too cold for these
migrant species and sadly few return to the
Continent or North Africa. However, while they are here, they
produce another generation of butterflies to grace both our
gardens and our countryside.
The red
admiral is one of our most recognisable butterflies, its
stunning pattern of red, black and white making it a firm
favourite with many people. An increasing number of individuals of this species
are spending the winter here in hibernation, and others migrate in
the autumn back across the Channel to Europe (they are
sometimes seen from cross Channel ferries!) but by and large
they are unable to survive our varying winter conditions
except in the warm Southwest. In its Central Europe home,
this butterfly hibernates where winter temperatures are
consistently very cold whereas many insects that hibernate in
the British Isles are fooled into untimely emergence when
temperatures fluctuate early in the year. A few warm days in
February are enough to waken a red admiral, but this early
emergence usually spells disaster. With no nectar available
and fat reserves used up, the survival of these individuals is
doubtful. February mild spells are often followed by harsh
weather, which finishes off many butterflies that have emerged
early from hibernation.
We are
most likely to see large numbers of the red admiral in late
summer or early autumn. These are the offspring of those that
made the migration in the spring – the progeny of the insects
that you may be seeing in your garden in June. On arrival,
these intrepid flyers will feed, taking nectar from whatever
early summer sources are available. After mating, eggs are
laid on nettle leaves and the tiny black, spiky caterpillars
are sometimes obvious from the webs of silk they produce,
which stick the edges of the nettle leaves together. They
feed and pupate inside this protective tent, emerging in
summer to grace our gardens until the first frosts arrive.
During the summer these insects are especially attracted to
Buddleia, Michaelmas daisies and Vebena bonariensis. They also
enjoy the nectar from late ivy flowers and the juices of
rotten fruit.
If the
conditions are good we should also see another migrant species
this month. The painted lady is a butterfly that is unable to
over-winter at all here but that may change as temperatures
increase. It simply does not have a
hibernation stage in its life cycle, relying on a continuous
succession of breeding in North Africa and Arabia where it is
resident. However, large numbers of this insect can reach our
shores in some years, especially if the weather conditions and
prevailing winds are favourable. 1996 was an amazing ‘painted
lady year’ when it was just about the most common butterfly
around. Huge numbers of this butterfly arrived on our shores
in May and June and moved northwards throughout the country
dominating Buddleias and other favourite nectar plants such as
thistles and the wild field scabious. We never know until
migration starts just what sort of influx there might be.
On
arrival on our shores in late spring, painted ladies seek out
thistles, their preferred larval food plant, on which to lay
their eggs. Nettles will also be used - these are also the
larval food plant of red admiral, small tortoiseshell and
sometimes the comma. Fortunately there is generally no
shortage of these plants on farmland and roadsides. This
means that the painted lady has plenty of opportunities to
breed and in good years there can be huge ‘home-grown’ numbers
of this beautiful butterfly. The caterpillars are much like
those of the red admiral being black and spiny, and they also
produce a tent of leaves in which to shelter. After pupation
these butterflies emerge in the summer months to feed on
Buddleia. They also enjoy the nectar from scabious,
Echinops and statice. Sadly the majority of these individuals perish
unless weather conditions enable them to make the long journey
back to Europe and North Africa.
Throughout the summer other butterflies along with these two
species migrate across the Channel to our shores. The bad
news for those amongst us who grow Brassicas, is that the
large white is one of these travelling insects. They too can
arrive in the summer in large numbers, boosting our homebred
insects. Rather less problematic is the wonderful clouded
yellow, a bright butterfly that again can produce massive
influxes of individuals. Migrant moths are also very common,
although less often seen by most of us. Only the day-flying
hummingbird hawk moth regularly reveals itself to observant
gardeners, feeding on tobacco plants, phlox, Buddleia, Verbena and honeysuckle.
The
phenomenon of insect migration means that some species of
butterfly are a great deal more mobile than we might realise.
This is good news for those of us who like seeing these
insects in our gardens – their mobility means that there is
always a chance of catching a glimpse of a rare clouded
yellow, or seeing a group of red admirals feeding on fallen
plums beneath a tree. |
