More people have received cleg bites due to the spell of warm weather, says the Royal Pharmaceutical Society in Scotland.
Aileen Bryson, from the Society, said they had received reports of the flies biting.
She said this was because people were spending more time outside in the sunshine, and having more skin exposed.
She said horsefly bites can be more painful than midges', and can result in red, fluid-filled blisters.
In most cases pharmacists can offer advice on treatments, she said.
Ms Bryson added that insect repellents and wearing loose summer clothing can help people to avoid being bitten.
Outdoor pursuits body, Mountaineering Scotland, said in warning issued on Monday about the warm weather that it had found clegs to be "thriving."