Rodents sneak under doors, through cracks and even down the drain looking for a meal, warn the exterminators.
It is believed that the pests become more and more desperate as their food sources decrease while people stay indoors.
The British Pest Control Association (BPCA) is a leading authority on rodent control.
The group said that about half of the professionals interviewed during the lockup saw their activity increase.
Natalie Bungay, BPCA technical manager, said: “Rats in particular may become more visible in population areas.
“With less trampling through towns and villages, there is less associated food waste in the trash cans and on the floor.
“As a result, rat populations are likely to move further to meet their need for a food source and this, in turn, is likely to cause more sightings.
“By nature, rats will also try to avoid humans directly, and therefore, with fewer of us walking the streets, they may become a little more daring and perhaps be seen in areas where they would not not normally.
“When it comes to rats in homes, as long as you manage your food waste properly and there is no considerable accommodation, you should not experience any unusual problems.
“The risk may be that if you find that you do more gardening and produce more garden waste, storing it in a heap around your garden can provide a perfect place for rats to live and breed.” . “
Pest experts working in households across the country say they have encountered similar problems.
Peter Higgs is the Managing Director of PGH Pest Control & Prevention, based in Cranleigh, Surrey.
He said his company has seen a 50% increase in house calls since the introduction of social distancing measures.
Speaking today (Friday), he said, “They are entering homes – that is exactly what is happening.
“All the trash that has been produced by people who eat food and by establishments that cook – it’s over.
“I think that some collections of garbage cans are not as frequent at the moment too. They fall into the trash.
“When they are hungry, they will eat each other. They will use a hierarchy in the cities – the big rats will eat the smallest.
“They will come using the drainage system – they eat excrement.
“They transmit diseases. A professional must be called to deal with the problem.
“We don’t want people to try to fix it themselves and use their own poison and contract something – they have to stay away.
“It is really important that they get an expert. “
When the lockout was first announced, some people started to store food, worried that the supermarkets would run out.
But a leading organization recently warned of the dangers of doing so – fearing that it would further encourage rats on residential properties.
The National Pest Technicians Association said rodents could enter without people knowing and causing problems.
Technical Director John Hope said, “It is the same as when trash is piling up on the street due to the missed garbage collection.
“The more there are, the more likely it is to attract rodents without actually seeing them, as they can go unnoticed when you reach the bottom of the pile.
“Storage will have an effect on public health because if you store goods, there is more food to attract rodents. “
Reports from other countries suggest that the problem – caused by the coronavirus – is not limited to Britain.
Urban rodentologist Bobby Corrigan believes that cities around the world are affected after being forced to close restaurants.
And he said cannibalism is a very real possibility – especially when the options are running out.
He told NBC News, “These rats that lived in this restaurant, a nearby place, and maybe for decades having generations of rats that depended on the food in this restaurant, well, life doesn’t work anymore for them, and they have only a couple of choices.
“So these rats are fighting with each other, now the adults are killing the young in the nest and cannibalizing the puppies.” “