Estimate given for biting midge numbers in Highlands

Highland biting midges on a man's hand

An expert on the Highland biting midge has said there could be an estimated 21 billion of the tiny insects in the Highlands and Islands.

Dundee-based Dr Alison Blackwell and her team made their calculation by looking at how many midges could be found in a square metre area.

Their estimate is for inland areas of the Highlands and Islands where the insect is mostly commonly found.

The figure of 21 billion is for females, which feed on blood.

They need blood to mature the eggs they carry. Males feed on nectar and other natural sugars.

'First explosion'

Dr Blackwell, who runs the Scottish Midge Forecast, told BBC Radio's Good Morning Scotland programme that because of their tiny size, there was a high mortality rate among biting midges.

However, she added: "We reckon that in a total season we might be close to around 69 billion midges at least for the Highlands and Islands."

She said when the 1:1 male to female ratio along with other factors, such as females that fail to find food, were taken into consideration, there were likely to be 21 billion females in a season "looking for a blood meal".

The biting midge season starts in May, when juveniles begin emerging from boggy soils, and continue through to autumn.

Dr Blackwell said the recent mild winter would have helped midge survival rates and, if rain comes soon, the "first explosion" of midges could come at the end of this month.

Scotland is also home to non-biting midge species.