The Scottish Midge Forecast said the insects hatched within a shorter timeframe this year because of a cold spring followed by a warm spell.
Dr Alison Blackwell said this resulted in a large first hatching with more minor geographical variations.
She said if it remained damp or humid, she would expect a “mega second generation” to start hatching.
The tiny biting insects thrive in wet and warm conditions and usually have two hatchings during the Scottish summer.
Last year dry conditions made life difficult for the midges, but Dr Blackwell said there had been sufficient humidity this year to help them survive.
“Now we’ve got a big starting population, it means that the levels will stay quite high throughout the summer probably unless there’s a dry heatwave,” explained Dr Blackwell, who runs the forecast.
The coming week looks set to be wetter, which, if it continues, could provide the ideal conditions for the second hatching.
Alert Raised as Abundance of Midges Emerges after Warm Weather
Midges usually spend the winter in the soil as larvae until the days get longer and warmer in the spring, which initiates them turning into adults.
Dr Blackwell added: “We generally expect the first peak of adults in the last week of May, the first week of June.
“That appears to have been delayed because of the colder weather we had at the beginning and middle of May.”
The coming week looks set to be wetter, which, if it continues, could provide the ideal conditions for the second hatching.
Midges usually spend the winter in the soil as larvae until the days get longer and warmer in the spring, which initiates them turning into adults.
Dr Blackwell added: “We would generally expect the first peak of adults in the last week of May, the first week of June.
“That appears to have been delayed because of the colder weather we had at the beginning and middle of May.”
The Scottish Midge Forecast usually finds higher numbers of midges on the west coast of Scotland.
Warning in Effect as Warm Weather Spurs Unprecedented Hatch
Dr Blackwell said this was because the insects breed in damp, peaty soil, naturally occurring in the country’s western half.
She added: “It also tends to be a bit milder, which is better for their activity.
“The winters are less cold usually than the east coast, so you get a greater survival rate of the overwinter larvae as well.”
Dr Blackwell, director of APS Biocontrol in Dundee, which runs the Scottish Midge Forecast, said midge numbers were predicted through modelling and some live data.
“We have a series of midge traps across Scotland, and people collect data for us,” she said.
“We also model populations based on years of population and weather data so that a set of algorithms primarily drives our forecast.”
Midges do not transfer any dangerous diseases to humans, so the work of the forecast is mostly to predict “peak nuisance levels”.
They can transmit some diseases to sheep and cattle, although it is uncommon in the UK because midges die out over winter.
“In the past, we have had infected midges blowing to the UK from mainland Europe carrying diseases like bluetongue virus,” said Dr Blackwell.
“Back in 2007, we had the last bluetongue invasion of Scotland and the UK. It was important then to map where midges were so that the livestock industry could be aware of that too.”
Midges are a frustrating and inconvenient part of a Scottish summer for most of us, so why do they exist?
Dr Blackwell said they are an essential part of the natural ecosystem.
“The larvae, the juvenile stages are probably most important because they’re like mini earthworms,” she said.
“They live off decaying plant matter, so they’ll be part of that whole food chain, decomposing plant matter back into carbon sources.”
She added that the adult midges also formed part of the diet of small birds and bats.
Those planning on visiting Scotland this year have been warned that the country is set to have a “bumper year” for swarming, blood-sucking midges.
According to leading expert Dr Alison Blackwell, the unusually mild winter and wet, warm spring start have put the perfect conditions for the insects’ larvae to thrive.
