The cold spring has delayed the dreaded return of the Highland midge.

But a leading expert is predicting that, despite the late hatch, there will soon be a population explosion of the pest.

Dr Alison Blackwell, director of Advanced Pest Solutions of Edinburgh, said: "It has been so cold that we have had very few reports of any midges. Only now there have been the odd one or two being spotted.

"The main first hatch usually comes in May, but we have had reports in previous years – when it was warmer – of people even being bitten in late March."

Dr Blackwell added: "The cold weather has slowed them down emerging this year but they will hatch with a vengeance once it warms up. They like it wet and warm – so far we have had the wet but not the warm. When that changes watch out."

The Scottish tourism industry is estimated to lose about £286 million a year because of the voracious insects, found Edinburgh University. A previous study also found that many tourists said they would not return to Scotland because of culicoides impunctatus – the tiny Highland midge.