Hopefully since March or April there have been butterflies in
your garden, flitting between your flowers, feeding on the
nectar on offer and providing you with a great deal of
interest. The last few summers have been widely reported as
being poor for butterflies and that’s not at all surprising.
Extremely wet weather or cool summers make life difficult for
all stages of the butterfly’s life cycle but especially the
larval and pupal stages. Caterpillars do not like wet
conditions as they are prone to fungal diseases when
vegetation is damp and pupae may fail to hatch in a cool humid
environment. This can mean that numbers of our summer
butterflies vary tremendously from year to year. There is little we can do
when numbers are low except ensure that we have provided
plenty of nectar for the adult insects that have made it this
far. But this might be a good time to put a little
thought into ensuring that our gardens are good habitats in
which butterflies can breed and set up home, rather than just
to do a bit of nectar-shopping. It is all too easy to
forget that the beautiful coloured-winged insects we are
seeing in our gardens now are just one phase in a complicated
life cycle, and in order to help their numbers increase again
we need to ensure that all stages of that cycle are
accommodated in our gardens, even if that means a few chewed
plant leaves!
I’m sure the butterfly life cycle was something
we all learnt about at school, possibly involving tending a
few ‘cabbage white’ caterpillars to enable us to see at first
hand one of the miracles of nature. I can still remember
the astonishment I felt at seeing a pristine white butterfly
emerging from a pupa, which had previously been a rather
grubby caterpillar! It’s a transformation we all take
for granted but it is none the less a complicated process.
The change between egg and caterpillar, pupa and adult winged
insect has many chances to go wrong. In fact research on
these creatures has estimated that only two eggs in a hundred
reach that final life stage. Compared with the success
rate of forty per cent survival of blue tits from egg to adult
in their first year, butterflies really do have a hard time of
it. Even the ‘cabbage whites’ deserves a break when the
odds are so stacked against them.
Mid summer should see a good number of
different species in your garden even if numbers of
individuals are low. Most of our spring butterflies species
should have bred successfully by now - the early peacocks,
small tortoiseshells, brimstones and commas have hopefully
completed a single life cycle. If you are seeing these
insects around your flowers this month they will be second
brood adults. These butterflies are noticeably less battered
and more brightly coloured than the spring individuals which
may have torn and ragged wings – spending a long winter
outside has many drawbacks. The early insects were the lucky
few that successfully survived the winter cold by hibernating
in sheltered nooks and crannies, deep in ivy against a fence
or wall or maybe in your garden shed. On emergence their
first instinct is to find nectar and their second is to breed.
A female brimstone will seek out the leaves of the native buckthorn
shrub on which to lay her eggs and nothing else will do.
She can detect the scent of these plants from some distance.
Peacocks and small tortoiseshells place their eggs on fresh
spring nettle growth, preferably in a light sunny spot and the
comma too will choose nettles, although in my garden they
always use wych elm as an alternative.
All these familiar early breeders will have
been joined now, hopefully, by many other native species plus
their numbers will have been augmented by the migrants that
visit us in the summer from the Continent and Africa. These
include the red admiral, painted lady and sometimes the
clouded yellow, a wonderful bright yellow butterfly that
occasionally arrives in great numbers. It seems extraordinary
that such apparently flimsy insects can travel such great
distances but they often travel here via warm southerly winds
apparently sometimes moving at quite high altitudes. On sunny
days on the south coast however, it is possible to see red
admirals arriving low across the waves – quite an
extraordinary sight. There is growing evidence that rising
temperatures are increasing the likelihood of the arrival of
yet more species from more southerly climes, plus some of
these migrants are managing to successfully spend the winter
with us. Red admirals are now quite frequently seen in the
early spring months suggesting that they are sometimes able to
survive our winter weather, especially in the south, by
hibernating in the same way as the small tortoiseshell and
peacock do.
At this time in the summer the only garden
butterfly we are unlikely to see is the orange tip. This
species only has one life cycle per year, the adult emerging
in April or May. However there should be plenty of others
around feeding on their favourite nectar sources.
In mid
summer there is not much we can do about the natural reasons
for t low survival rates of our native butterflies – the vagaries of the
British weather take their toll every year - but we can do
much to give butterflies a helping hand by providing nectar
and more especially, larval food plants. It is surprisingly
easy to accommodate the food plants of many of our native
species but I would tend to avoid nettles in the garden. By
and large they are plentiful in the countryside (especially
where heavy doses of nitrogen fertilisers are used) in
hedgerows and on waste ground even in cities. In the garden
they can take up a great deal of space and need to be in a
protected sunny spot for the red admirals, peacocks and small
tortoiseshells to deign to use them. Keep that sunny spot for
a relaxing bench! However, many of the other larval foods can
be added to borders, planted under hedges or, if you have a
meadow area, will grow (or already exist) in that long grass.
Most of
the smaller common garden species can be catered for easily.
Orange tips and green veined whites will both choose sweet
rocket (Hesperis) and honesty if the wild lady’s smock is not
available. These all flower at just the right time to provide
nectar for the adult insects, and food for their
caterpillars. Both common and holly blue could be around
your garden. They will be looking for bird’s foot trefoil and
the flower buds of ivy respectively (holly is the food plant
of the earlier spring brood). If you see small blue
butterflies flitting about at the top of an ivy covered wall
this month, they will be holly blues. Of the other smaller
native butterflies, small copper and the large and small
skippers are likely to be garden visitors if only
occasionally. The small copper lays her eggs on sheep’s
sorrel, an attractive plant which can be added to a meadow
area. This wildflower is doubly useful - try the leaves in a
cucumber sandwich for a refreshing lemony tang! Hairstreaks
sometimes pop up in more rural gardens, especially those with
elm suckers in the hedgerows round about. The white letter
hairstreak once thrived on the leaves of these wonderful
trees, now ravaged by Dutch elm disease, but a much-reduced
population of this gorgeous little butterfly can still be
found. The brown argus is increasing and lays her eggs on the
leaves of dove’s foot cranesbill, a common lawn flower.
But a meadow is the key to increasing the
number of butterfly species that will breed in your garden.
Our wild, fine leaved native grasses are the larval food
plants of the meadow brown, ringlet, speckled wood, marbled
white, wall brown and gatekeeper, plus the skippers mentioned
earlier, all of which will visit and breed in gardens. The
wall is now sadly much in decline and marbled white is more
likely to visit a rural garden but the others will appear in
most locations if long grass is available for them to breed
on. A fully-fledged meadow is not essential as long as long
as the grasses are fine-leaved native species such as the
fescues and timothy and are left uncut for the whole of the
summer. Cutting should only take place at the end of
September, and the grass left at a height of approximately 5
cms or more. Plug plants of larval food plants can be added in
autumn or spring, plus some good nectar plants including
knapweed, scabious and oxeye daisy.
Something as simple as adding honesty to your
borders or the base of a hedge, or creating an area of long
native grasses with bird’s foot trefoil, sheep’s sorrel,
dove’s foot cranesbill, and some nectar plants, could help our
butterflies survive another wet summer. |
