Midge problems at the 2007 race led to the trials
Hundreds of competitors taking part in a gruelling Scottish race are to test a new midge repellent.
Up to 1,000 athletes will take part in the First Monster Challenge, a 120km running and cycling race around the shores of Loch Ness in September.
Researchers from the University of Aberdeen will use the event as a major survey to test a new spray which they hope will combat midges.
Competitors will be asked to use the spray, made from natural chemicals.
The decision to use the event, organised by transport company FirstGroup, was prompted by last year's race.
Organisers said feedback was mostly positive - except for complaints about a spate of midge attacks at one point on the course.
One participant was said to have suffered hundreds of bites, so this year's race will be used as a test-bed for the spray.
The tiny swarming flies are a persistent nuisance for tourists, and there have long been fears the insects are a turn-off for visitors.
The sub-species in Scotland is known as the Highland Midge, and is infamous in the north and west of the country.
Female midges bite, and are attracted to carbon dioxide and other chemicals released from human breath.
Scientists estimate that in one hour a swarm of the insects can inflict about 3,000 bites and 40,000 midges can land on an unprotected arm over the same period.
Tourism experts put the cost of the pests at £286m a year, as some visitors opt for locations which are not plagued by the insects.
The new midge repellent is based on chemicals discovered by the University of Aberdeen and Rothamsted Research. It was formulated as a puffer repellent by Atrium Innovation.
Researchers claim the repellent could be "the most effective ever invention to combat the midge".
Prof Jenny Mordue, from the university's department of zoology and an expert in midge behaviour, was involved in developing the spray.
She said the event was an opportunity for "a monster trial in the age-old battle between man and midge".
"I am confident the results from the experiment and survey will help shape and develop our strategies on how best to combat the midge," she added.
"If all goes well, we will finally have a solution in the battle to protect people from the dreaded midge."
Two tents will be used to test the new formula. In one, the repellent will be released into the atmosphere and in the second it will not.
Researchers will then see which attracts the most midges.
Athletes and spectators will also be asked to fill out a questionnaire about how susceptible they are to midge bites.
Prof Mordue said if the experiment went well, the new substance could be developed into creams, lotions and even specially-designed clothing or badges impregnated with the chemicals.
But it would be one or two years before it would be available, she added.
She said: "It is a totally different mode of action, totally new. It stops the insects from flying towards you.
"It is developed from natural chemicals that we give off."
This is in contrast to synthetic alternatives currently available, she said, which only repel the insects once they make contact with skin.
The First Monster Challenge takes place on 13 September.