You can't see them, you can't hear them, but when they bite you definitely know it. Yes, the blood-sucking blackfly has returned to Oxfordshire, writes Paul Harris.

The blackfly, or Blandford fly, is just 2mm long, but its bite causes painful swellings which can last for weeks.

Judith Carrington, 35, of Brinkinfield Road, Chalgrove, is on a course of anti-histamine tablets after falling victim to the tiny bugs, which leave pinpricks on the skin.

She said: "A day after the bite, my ankle was very red and extremely swollen, painful and blistered. "You cannot see the flies, or feel them. Some people are more susceptible than others.

"A lot of people are being bitten and not everyone is reacting. Those who do react, do so very badly."

Mrs Carrington fell victim to the insects last year. In May 1998, at least a dozen cases were recorded by doctors in the Cherwell valley.

Oxford, Woodstock, Deddington and Kidlington were most badly affected.

Immediately after you are bitten a toxin is released on your leg and it is not until an hour or two later that your leg begins to itch and swell. Ankles are particularly vulnerable to the bites.

Oxfordshire people first began complaining about the blackfly, which was discovered in Blandford, Dorset, in the summer of 1995, especially on the River Cherwell between Heyford and Shipton.

It can also be found on the River Thame, the Thames, the Windrush and the Evenlode.

Oxfordshire Health Authority spokesman Steve Argent said people walking near the Cherwell river should wear trousers and use insect repellent.

Story date: Wednesday 12 May

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