Sun revellers are being warned by NHS England to be on alert for the blood-sucking Blandford fly, after cases related to the insect bite have dramatically increased in recent months.
The fly bites can potentially leave victims seriously ill, with extreme reactions resulting in swelling in the groin and a fever.
Other symptoms include swelling and blistering.
Increase in cases
The warnings come after several cases were reported earlier this month.
The 2-3mm black fly thrives in warm weather – and the recent rise in temperatures has ripened conditions for the bloodsucker.
Karen Wright, director of Public Health for Herefordshire, said as the mercury rises it is likely there will be more cases of Blandford fly bites.
Beware rivers and streams
She said: “We encourage people to take precautions if they’re out and about on rivers and streams, especially over the forthcoming bank holiday weekend.
“If you do get bitten, it can often feel very uncomfortable with swelling, blistering, joint pain and sometimes high temperature.”
The NHS recommends people cover up arms and legs and use insect repellent when out and about near affected rivers and streams.
Ms Wright added: “There’s normally no need to visit a GP.
“If you do feel unwell after a bite, please call NHS 111 or visit your local pharmacy for advice on how to ease your discomfort.
“For the majority of people, the symptoms will only last a few days before clearing up.”
The Blandford fly usually targets the ankles and legs while flying low to the ground, and some of the most serious reactions to its bites include swelling in the groin, fever and painful blisters.
The notorious pest got its name after an outbreak of residents being bitten around Blandford in Dorset in the 1960s and 1970s.