For many of us, our first significant encounter with a ladybird comes in late winter, and surprisingly for a beetle that is just 5mm long, this meeting often bears a striking resemblance to an over-egged scene from a horror film.

This meeting does not take place in the soul-replenishing setting of the great outdoors but in the more humdrum environs of our homes, usually while we are gazing out the window contemplating the arrival of spring. Our daydreaming is brought to a swift and abrupt end as we notice a red ooze, dribbling ominously from the corner of the window frame.

On closer inspection, this ooze reveals itself to be beetles, ladybirds in fact — hundreds of them, gyrating and scrabbling uncontrollably as they emerge from a tiny crevice in the windowsill that you never knew existed in the first place.

And the chances are that the individuals in this red plague are members of an invasive species of ladybird that has been described by environmental charities as a “wildlife and heritage disaster”.

Since 2003 the Asian harlequin ladybird has attracted the kind of bad press now reserved for Antipodean media moguls of a certain vintage.

The interloper arrived in the UK, as ever from America, as a means to control aphids.

But, in less than a decade, the harlequin has advanced as far North as Orkney and as far West as Pembrokeshire.

In its wake it has left a wave trail of destruction that threatens the very survival of many of our much-loved native ladybirds.

But it was not always thus. For hundreds of years our ladybirds have basked in the glory of being the nation’s second favourite insect behind our over-the-top show-offs — the butterflies. We have bestowed upon the far more workmanlike ladybird colloquial names such as the bishy barnaby, a title so obscure that nobody now living has the faintest idea as to what it means.

Much loved by gardeners, ladybirds have fought on our behalf in the endless war waged on aphids.

And this revered bug even enjoys religious connotations. The name ladybird is derived from our most common native species — the seven-spot ladybird (we have 47 species in all). The red colouration is supposed to represent the Virgin Mary’s red cloak, the insect’s seven spots a nod toward her seven joys and seven sorrows.

The ladybird is not only saintly but can also boast to being the sexiest bug in Britain.

Who can forget the television advert featuring two overly amorous ladybirds getting extremely well acquainted to the backing music of Serge Gainsbourg’s raunchy hit Je t’aime.

So what exactly has the harlequin done to unravel centuries of good press?

Well, the beetle’s biggest problem is that like the invading grey squirrel, it is bigger, stronger and more competitive than our native species. Unlike most other ladybirds, the harlequin doesn’t stick to one food type such as aphids, its enormous appetite extends to other ladybird eggs and even those of moths and butterflies.

Conservationists are concerned that the adaptability of the harlequin, which is named after the fact that it can appear in more than 100 different colour patterns, could threaten the long-term survival of some of our native ladybird species.

Matt Shardlow, from wildlife charity Buglife, said: “We know from laboratory studies that harlequin ladybirds are very effective predators of native ladybird larvae and compete with adults of native ladybirds for food. It is not surprising, therefore, that as the populations of the harlequin ladybird expand so at least 10 species of native ladybird decline.

“We are losing the ladybird species that kept down aphid numbers in the fields that fed our forefathers, this is a wildlife and a heritage disaster.”

Our ladybirds are endlessly fascinating and come in a wide variety of colours, from the gaudy yellow and black 22-spot species to ladybirds that are orange and even black.

So it is now more important than ever that we start to take notice of these tiny beasts clambering through the undergrowth.

The key to helping our native species in the future is by monitoring where they are and how they are coping with the threat of habitat loss and their big bad brother — the harlequin.