Experts expect high numbers of rodents to take refuge in homes to escape fall rains.
Like much of coastal B.C., Nanaimo enjoyed plenty of sunshine over summer, and all that sun has made food plentiful.
It produces berries in the wild and in backyards, and an abundance of apples, pears and other fruit.
It's easy pickings for rodents, allowing them to produce bigger broods.
The city doesn't track rodent population data, but exterminators say with all the sunshine this summer, it could well be a problem.
"What's concerning is the amount of fruit on the trees right now," said Dave Wiener, of All Pest Services.
"Any time there's an abundance of fruit, it increases the breeding population."
In a single year, two mice can produce 2,000 descendants under ideal conditions. A mating pair of rats can be responsible for 500 animals in the same period.
Wiener advises homeowners to block holes where rats can enter buildings, remove fallen fruit and trim tree limbs away from houses to prevent climbing rats from getting into attics.
The city is not responsible for controlling rodents, but Randy Churchill, city bylaw control manager, said his department does get the occasional call when a neighbour's compost pile or fruit tree is suspected in attracting the vermin.
Rat complaints rise when a grocery store or old building is demolished or renovated, "but then it goes away in time" Churchill said.
Rodent control was a constant battle for Loaves and Fishes until the food bank operator replaced its old warehouse on Farquhar Street two years ago.
"In the last year or two we haven't had a single bit of evidence of rodents in that warehouse," said Peter Sinclair, food bank manager.
It's still a problem outside the warehouse, and "we have a program to deal with it," he said. That includes trapping and poisoning the vermin.
"I personally don't feel great using poison, because of the environmental aspect, but the reality is, it ensures rodents aren't in with the food."
Traps are recommended over poison indoors, because "if a poisoned rat feels sick, it's going to go (inside) and die in your home," Wiener said.
"When that thing dies, who knows where it is?" A B.C. Ministry of Environment website says three of the roughly 20 rodent varieties in the province cause problems: The house mouse, Norway rat and black rat, which originated in Asia.
It's easier to remove rodents when they first appear, in small numbers.
It's a lot more difficult getting rid of established colonies, especially in barns or older houses with many entry points and hiding places.
Rats breed prolifically, so an ignored infestation will grow, and cause damage.
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