False widow spiders, considered Britain's most dangerous arachnid, are continuing to spread across the UK, with health experts warning that their bite can in rare cases trigger serious flesh-eating infections. The report highlights growing concern among medical professionals about the spider's expanding range and the potential for bites to cause severe secondary bacterial infections if not properly treated.

The article sets out guidance on recognising a false widow bite and the steps to take afterwards to avoid complications, given that the spider's venom, while not usually life-threatening on its own, can leave wounds vulnerable to dangerous infections. Note: the full article text was not available beyond the introductory details, so this summary reflects only the limited content provided.