Shhhh. Hear that noise? That's the sound of raccoons, squirrels and rats playing hide-and-squeak in the crawl spaces, attics and walls of homes across the Chattanooga area, fleeing frigid temperatures.
It's also the melody of young mosquitoes -- widely despised carriers of the West Nile virus -- perishing en masse as the region's deep freeze refrigerates this year's crop of embryonic bloodsuckers.
The cold weather is a mixed bag when it comes to pests. Some, like the southern pine beetle, freeze to death after a couple of days of ultralow temperatures. Others, such as the crafty raccoon, use the opportunity to find new homes.
"As soon as it starts getting cold, rodents start rushing into those attics and crawl spaces to get warm," said Blake Mitchell, Chattanooga Service Center manager for Arrow Exterminators. "Everybody starts hearing something at night, scratching noises and chewing, because rats and squirrels have huge front teeth, and they constantly chew to keep 'em wore down."
If the roof rats constrained their chewing to acorns and bark, things would be fine. But the critters have a particular affinity for water pipes, untreated wood and insulation, which they use to make warm nests for the coldest days of the year.
Calls for service to Arrow Exterminators jump from three to four a week to as many as 10 a day as the rodents scamper out of the icy wind and into the toasty homes of their human neighbors.
"All it takes is one," Mitchell said. "The rodents, they have a leaking bladder. And their trail leading out of the house tells everybody else how to get in there."
That's the bad news.
The good news is that many harmful insects are going to die. Fluctuating temperatures trick some of the bad bugs into hatching early. Then they're flash-frozen as the mercury falls again. Others are killed by cell-rupturing ice crystals that form during the thaw-and-freeze cycle.
"Compared to years past, we've had so many mild winters and those have led to some horrible mosquito seasons," Mitchell said. "I'm hoping all this extreme cold knocks that number way down."
But Bennett Jordan, entomologist and research scientist at the National Pest Management Association, said insects "have an astounding array of tactics that allow them to avoid freezing or just deal with it."
For instance, mosquitoes may have frozen in last week's single-digit cold, bu many of their eggs could have survived. And creatures like termites, stinkbugs and lady bugs often crawl into attics or under logs, riding out the winter in relative comfort.
"Mosquito eggs are very resistant to environmental conditions, and will remain dormant until the temperatures and water come into effect, then they hatch and resume as if nothing ever happened," Jordan said.
For mosquito populations, the biggest factor will how much rainfall the region receives as temperatures rise this spring. Hate mosquitoes? Pray for drought.
"If they don't have enough water to lay their eggs or the right conditions, it's hard to get around that," Jordan said.
Some insects have better than average survival instincts. Many can't be fooled into hatching prematurely by an unseasonably warm spring. Instead, they're programmed to wait for a certain day-night cycle before they emerge. A few beetles and midges produce an antifreeze compound out of synthesized ethylene glycol. Other insects can hibernate. Termites just dig a little deeper underground and continue business as usual.
And don't start celebrating the cold-weather demise of pests while forgetting that the predators responsible for eating those insects are often equally affected, Jordan said. Many of those creatures, which include birds, bats and lacewings, are less hardy than the bugs they eat.
"If they were harshly affected by the winter, they're going to be less likely to be able to keep the mosquito populations down," Jordan said. "Ecology is a complex balancing act."
Contact staff writer Ellis Smith at firstname.lastname@example.org or 423-757-6315.