Pest control experts have warned the population can easily become out of hand with mice able to produce a litter every 21 days from the age of six weeks.

The infestation isn't as bad as the "carpet of mice" reported in other parts of NSW and Queensland, but it's still significant.

Their presence around homes and rural properties is attracting snakes, and that has led to pets being bitten and an increase in calls to snake catchers.

"From Maitland out to Merriwa there are big rodent issues. It's a reflection of the change from a dry time to a time of good conditions," the Hunter's Tony Ceccato, of Australian Pest Solution, said.

"All the grass seeds are there for food and they've got plenty of grass cover from the owls and other birds of prey, especially in semi-urban areas.

"We've seen quite a few snakes when we've been out on jobs as well."

Mice have also been seen in the fields at the Hunter Valley vineyards and in farmers' paddocks.

While winemaker Bruce Tyrrell is yet to see them running between the grape vines, he picked one out of a bin of Semillon on Thursday morning.

Other pests are also making the most of the favourable conditions.

Termite, spiders and flea infestations are also on the rise.

Fleas breed rapidly when it rains after a dry spell and termites need moisture and thrive in damp conditions.

"There has been a lot of rain this summer and that has created a lot more moisture and seen pests become more active," East Maitland's Jacob Bell, of Jacob Bell Pest Control Services, said.

"There's a lot of building going on and a lot of ground being excavated and a lot of rodent nesting areas would have been disturbed so they would be looking for another place to call home. They like to find their way into the home or the ceiling or the shed to nest."

Mr Ceccato urged residents with birds of prey, and snakes and lizards, around their home to use baits that limited the transmission to other animals. He said catch and release traps were another option.

The recent heatwave has provided a small reprieve from snake sightings.

Snake catcher Judith Martin said snakes retreated to a cool spot on a hot day, just like us, and that had decreased the number of snake sightings during the day.

"People are seeing them later in the day, or even late in the evening, because it's too hot for them during the day.

"A lot of people think snakes like the heat but that's not the case."