Butterflies have long been among the prettiest visitors to the British garden, feeding on buddleia and other nectar-rich plants, providing movement, colour and interest for all, as well as being beneficial pollinators.

But the terrible summers of the last two years and the cold, wet weather in late spring and early summer have all contributed to a reduction in numbers, according to the charity Butterfly Conservation, the world’s largest research institute for butterflies and moths.

“This spring could have been catastrophic for butterflies, because it means we will have had three really bad breeding seasons in a row,” says Dr Martin Warren, the charity’s chief executive.

“We have evidence that even common butterflies such as the small tortoiseshell are getting much rarer.

Almost three-quarters of UK butterfly species have decreased in population during the last decade. Last year we saw a quarter less butterflies than in the previous year.”

The weather in recent years has just exacerbated the situation, Warren continues.

“In 2010 and 2011 we had a really bad July and August, as butterflies struggled to feed, fly and find a mate in the chilly conditions. The cold, wet weather in summer reduces their chances of survival.”

The charity is urging people take part in this year’s Big Butterfly Count, from July 14 to August 5, in which people record their sightings to provide the vital data which helps to determine how best to conserve the UK’s butterflies.

To enter, just find a sunny place and spend 15 minutes counting every butterfly seen and then submit sightings online at www.bigbutterflycount.org.

But it is also hoping that gardeners can help boost populations by encouraging a small patch of their garden to grow wild, so providing a vital haven for threatened species.

“Habitats where butterflies breed are becoming much smaller, as people have gone for formal gardens and more pesticide use. Butterflies tend to breed in long grasses and wildflower meadows, but much of that habitat has been lost.”

Leaving a patch of your garden wild doesn’t mean it will just be a mess, he says. Seeding it with herbs such as oregano, thyme and marjoram will not only provide rich nectar sources for butterflies, but will also be useful in the kitchen.

Buddleia has long been seen as the key species to attract colourful red admirals, peacocks and small tortoiseshells.

But less showy plants such as clover, ivy and daisies provide caterpillars and butterflies with much-needed food and shelter.

Steer clear of ‘double flowers’ as they tend to produce much less nectar than single-flowered varieties. F1 hybrid plants also usually produce very little pollen.

Spare a few brambles and nettles from the chop and plant some wildflowers and you will be providing your garden butterflies with a vital source of food and shelter.

The Big Butterfly Count runs from July 14 to August 5.