Flying visitors

As child it never occurred to me to worry about butterfly decline because the garden was full of them. This included Red Admirals by the dozen, the brave migrants from Europe whose scarlet, black and white wings remained inexplicably unscathed by their long journey.

Small Tortoiseshells too, their mottled orange wings fringed with blue, and Ringlets, Peacocks, Painted Ladies as well as the occasional Fritillary.

A shimmer of colour and flickering wings, their favourite nectar-rich food was the fragrant, violet flowers of the shrub known with very good reason as the butterfly-bush or Buddleja davidii .

Meanwhile, a ramble through the damp fields and woodlands nearby would always raise a small cloud of Meadow Browns and Orange-Tips. The latter liked to lay their eggs on the cuckooflowers, Cardamine pratensis , which grew there in abundance. At rest, their wings folded, they looked nothing much, but once they took to the air the males of the species would unveil their "plumage" with a sudden flash of colour – the bright orange a warning to birds that this butterfly would make an unpleasant tasting meal.

Like everyone, I’m saddened by the decline in butterfly numbers over the last number of decades, and by the fact that gardeners share some small part of the blame for this. Our sometimes indiscriminate use of strimmers and herbicides, for example, to “tidy up” roadside verges and the wilder edges of a garden damages potential habitats and destroys valuable food plants.

Our use of pesticides are harmful to both the young larvae and adults. Even the sticky insect traps we use in glasshouses or polytunnels to catch whitefly are just as effective when it comes to trapping the gossamer-light wings of a butterfly.

Instead, gardens, big and small, urban or rural, should be places of refuge for these beautiful, magical flying insects as their traditional habitats continue to decline as a result of intensive farming practices, the construction of buildings and roads, and climate change .

How? To start with, consider leaving even a few small patches of the garden to go wild, allowing weeds, wildflowers and native grasses such as nettles, dock and thistles to thrive. While this might sound the very opposite of good gardening practice, these plants are all valuable food sources for the larvae (the caterpillars) of different butterflies.

The Small Tortoisehell, Red Admiral, Peacock and Comma, for example, all lay their eggs on the leaves of the common nettle, as occasionally does the Painted Lady. The larvae of the latter are extremely fond of thistles, including burdock (the same plant, incidentally, whose spiky flowers inspired Swiss engineer George de Mestral to invent Velcro).

Other Irish butterflies – and we have 34 species that are either resident or regular migrants – include the Speckled Wood, Wall Brown, Grayling, Gatekeeper, Meadow Brown, Ringlet and Small Heath, all of which depend upon various native grasses as a source of food for their larvae.

By allowing even a few patches of wild grasses along the margins of the garden to remain uncut throughout the spring and summer you’ll be encouraging some of these species to visit (a few are quite rare). As for the dainty Holly Blue, its larvae (not unsurprisingly) are partial to the leaves of holly as well as ivy and pyracantha.

An adult butterfly also needs food, but of a very different kind. Unable to chew leaves, it instead relies upon its proboscis (a long, hollow tube rather like a straw) to suck liquid nectar from flowers, both wild and cultivated.

Some flowers are far richer in this sweet, nutritious liquid than others, while butterflies – whose vision is quite different to that of humans and extends into the ultraviolet spectrum – are also particularly attracted to vibrantly colourful flowers, especially in shades of dark pink, orange and purple.

Don’t forget seasonality. Gardeners often consider growing some summer flowering plants to attract butterflies into their garden, forgetting that these colourful insects need a steady supply of nectar from the moment the adult butterflies (of those hibernatory species resident in Ireland) wake up from their long winter hibernation and take wing in hungry search of food. The same is true of the hungry migrants that arrive along our shores in late spring, as well as the rare vagrant species. So if you want to attract butterflies into your garden, where they’ll hopefully lay eggs for the next brood, grow an array of nectar-rich spring flowering plants.

Some of these are what gardeners would traditionally describe as weeds – buttercup, dandelion, lesser celandine – while others include the dainty wild primrose and cowslip.

But many butterflies are also partial to the more traditional spring-flowering "garden" plants, including carpet-forming aubrietias, elephant's ears ( Bergenia cordifolia ), doronicums, hyacinths, wallflowers, scillas, pulmonaria, honesty, flowering currant, pussy willow and ornamental cherries. In late spring/early summer they'll happily feed from the flowers of sweet william, lilac and sweet rocket. For summer and early autumn, grow colourful, flowering annuals such as golden marigolds, sweet alyssum and 10-week-stock as well as plenty of ornamental perennials – the airy Verbena bonariensis with its violet umbels, Michaelmas daisies, Astilbe x arendsii , dahlias (single rather than double-flowering), sedums, phlox and herbs such as marjoram.

Of course, don't forget summer flowering shrubs. In full flower, the butterfly bush, Buddleja davidii , serves as such a remarkable butterfly magnet that it's not unusual to see dozens of these colourful insects feeding from its nectar-rich blooms. Keeping in mind butterflies' predilection for brightly coloured flowers, choose a variety with deep pink, lavender or violet flowers rather than one with paler blooms.

Other butterfly friendly, nectar-rich summer flowering shrubs that you might consider growing include escallonia, lavender, rosemary, species of viburnum, potentilla and ceanothus as well as privet. Remember, too, that most butterflies are happiest in sheltered but bright gardens where they can bask in the sun’s warm rays (another important source of energy). Finally, don’t forget that our resident hibernating species also need a sheltered spot in which to rest during the cold winter months. This might be an old outbuilding, a hollow tree stump or even the eaves of a house roof.

It should be pointed out that it’s not all doom and gloom as regards the future of Irish butterflies. The Irish Butterfly Monitoring Scheme, which has been in operation for seven years, recently reported that 2013 was a good year for these beautiful insects, with populations up by as much as 32 per cent compared to 2012. While populations naturally fluctuate from year to year (and 2012 was an especially bad year for butterflies) much of the increase is due to last year’s golden summer. From the data collected so far by the scheme’s volunteers (and they are always happy to welcome new volunteers), it’s clear some species are still in steady decline, including the Small Tortoiseshell, the Speckled Wood and the Wood White. But in steepest decline is the ‘Banóg mhór’ or Large White, one of two butterflies that gardeners call the cabbage white because it likes to lay its eggs on the leaves of brassicas, and which was often commonly seen in fields of oilseed rape. But only fields of oilseed rape that hadn’t been sprayed with insecticides.

So perhaps it’s time we gardeners also take a slightly more generous approach to a butterfly we’ve traditionally seen as a garden pest. This summer, while I’ll still cover my brassica crops with Bionet, I’ll also be growing a few elsewhere in the garden, especially for the butterflies.