Up to 300million "super rats" are feared to soon be plaguing the UK - after becoming obese eating fatty takeaway scraps.
Experts say the rodents are gorging on leftovers strewn on streets and overflowing bins as the nation's diet has become increasingly unhealthy.
It's believed rats have also grown resistant to rodenticides, which have been used since the 1950s.
Craig Morris, a pest controller with 15 years of experience, said: "Rats are becoming more of an issue. They are one of nature’s amazing survivors. They have exploited everything we do and done it really well.
"What might sound horrific to most people is just an everyday occurrence to me, I’m afraid."
The 53-year-old man, who operates across Hampshire, Dorset and Wiltshire, told Daily Star poor sanitation and hygiene has also led to the boom in rat population recently.
But the country's dependence on calorie-laden fast food is also behind the surge, Mr Morris said.
Last month, a McDonald's customer was left horrified after spotting up to seven rats climbing in and out of a bin in the car park of a Hull restaurant.
Scenes like this have concerned ecology researchers.
Steve Belmain, a professor of ecology at the Natural Resources Institute at Greenwich University, London, said of the UK’s rat numbers: “I could easily imagine 200 to 300 million rats here.”
Prof Belmain is aiding a project in which rats are being trapped across livestock farms in Norfolk and Essex to test for the prevalence of disease.
It is happening because a study in December last year claimed around 78 per cent of rats had developed genetic resistance to anticoagulants.
The biggest rat on record to have been caught in Britain, by a Bournemouth pest hunter in 2018, measured 21 inches in length – as big as a small dog.
