SOUTH LAKE TAHOE, Calif. – A decade ago, nobody reported seeing rats in their homes around the South Shore of Lake Tahoe, but that has now changed. Exterminators are very busy responding to calls about rats from Fallen Leaf Lake to Glenbrook and all points in between. A quick glance at social media will reveal that they are a problem and a growing concern.
The first Norway rat call Lakeside Pest Control responded to in South Lake Tahoe was in 2014, and it was a single call near Ski Run Boulevard. This year, they are responding to numerous calls in every neighborhood in the South Shore.
Boulder Exterminators has been very busy this winter, and spring is no different as they respond to calls about rats, along with the more normal calls of mice and spider infestations. They are seeing mostly roof rats and wood rats.
RATS
Rats are smart. They can figure out how to evade humans and traps. Instead of that lone report in 2014 of a rat, there are now sustained populations in every single neighborhood along the South Shore. Walk into DIY Home Center or any other retailer of rat traps, and you’ll find you are not alone in trying to find the tools needed to trap the pesky and intelligent rodents.
Many who work in the outdoors say they have started seeing roof rats over the last three years, but say the Caldor Fire didn’t drive them to South Lake Tahoe, as they were seen in the area before then.
Why there are more rats now is a question that is hard to answer. Some point to trash and waste in the meadows and other outdoor areas where the homeless may gather, and others say the rats “hitchhiked” on a delivery truck and decided to stay. Dozens were found and trapped in a South Lake Tahoe home about four years ago.
Aimee Dhondt, owner of Lakeside Pest Control, said forms of transportation can deliver more than goods. She said diseases were spread by ships hundreds of years ago, and now the rats can be moved around by trucks. She said rats are finding new food sources in areas where backyard chicken coops are built, and that those attract rodents with their food supply just like a cluttered home does.
“Rats aren’t stupid; they look for opportunities,” said Dhondt.
Roof rats, also known as black rats or Rattus rattus, reach sexual maturity around 2-3 months and can breed year-round, with peaks in spring and fall, producing 4-6 litters annually, each with 6-8 pups. Females build nests out of sticks and leaves, usually in the upper floors of buildings or trees.
Norway rats, or brown rats or Rattus norvegicus, reach sexual maturity around 3 months of age and can breed throughout the year, with breeding peaking in spring and fall, and females can have multiple litters per year (up to 12). They reach sexual maturity around three months. Females can come into heat every 4-5 days and can mate within 1-2 days after giving birth.
Lake Tahoe isn’t the only area seeing an increase in rat populations – it is widespread. The Norway rats are foragers that can survive on a wide range of food, which has helped them successfully spread across the world.
Roof rats and Norway rats differ in size, appearance, and behavior, with roof rats being smaller, sleeker, and better climbers, while Norway rats are larger, stockier, and prefer ground-level areas. The roof rat lives in trees and above homes, orchards, and yards, while the Norway rat tends not to live outside – they burrow near buildings and don’t travel. Roof rats can come from pipes and jump two feet.
Roof Rat – Smaller and sleeker than Norway rats; Typically have black or dark brown fur with a lighter underbelly; Longer tails than their body length; Have pointed noses and large, hairless ears; Average weight: 5 to 9 ounces. They are excellent climbers, often found in trees, on roofs, and in attics, and they nest in high places, such as attics, wall voids, and soffits, and may be found in houses, grocery stores, and restaurants. They are known to cause damage in high places, such as chewed wires in attics. Roof rat droppings are smaller and pointed.
Norway Rat – Larger and heavier than roof rats; Have brownish-gray or reddish-gray coats; Have shorter tails than their body length; Have blunt noses and small, close-set ears; Average weight: 12 to 16 ounces. Burrowing rodents, often found in basements, crawl spaces, and around foundations, nest in ground-level areas, such as under buildings, in piles of debris, or in burrows, and may be found in garages and other lower areas. They are known to cause damage in low places. Norway rat droppings are larger and more blunt than the roof rat droppings.
Rats can cause damage in and around homes and vehicles. Roof rats are known for causing damage in high places, such as chewed wires in attics, while Norway rats are known for causing damage in low places, such as burrowing around foundations. Both are omnivores, but roof rats may prefer fruits and nuts, while Norway rats may prefer grains, nuts, and pet food.
Rats are now used to living near humans. They like to hang out in wood piles, so it is important to keep piles away from the house (besides just to be fire safe), and they also like yard debris as their home.
MICE
After actor Gene Hackman’s wife died from Hantavirus in Arizona, and shortly after, Mono County announced three deaths from Hantavirus, the deadly virus that comes from deer mice. Mono County Public Health said, “We believe that deer mouse numbers are high this year in Mammoth (and probably elsewhere in the Eastern Sierra). An increase in indoor mice elevates the risk of Hantavirus exposure. Therefore, it is crucial to take precautions.”
California Department of Public Health (CDPH) says Hantavirus is a rare virus that spreads through the urine, droppings (poop), or saliva of wild rodents, including deer mice, which are common in many parts of California. Hantavirus can cause serious disease in humans. The rate of infection has been low in California – 79 cases between 1980 and 2024, but with the recent deaths in Mono County, there is concern that it could be spreading.
According to the CDPH website, people can become infected with Hantavirus when they breathe in air that is contaminated with the virus. Particles containing hantavirus get into the air when dried mouse urine, saliva, or droppings are stirred up. The chances of this happening increase when opening or cleaning buildings in rural areas that have been closed for the winter, where deer mice have entered, or for people working, playing, or living in closed spaces where mice are present.
There is no vaccine, and no magic shot to cure the virus since it is just that – a virus. People can survive the virus that affects the respiratory system, but it a few cases, it can be deadly.
Mice are no strangers to Lake Tahoe homes, but much easier to trap than the rat. They follow other mice scents and body oils as they travel along baseboards in a home.
REMOVING AND CLEANING UP AFTER RODENTS
People who find droppings in their home should clean up immediately, but there are proper ways to clean to prevent Hantavirus from spreading. Sunlight and airflow kill the virus.
- Do not sweep or vacuum – This can stir up droppings or other materials contaminated with hantavirus into the air.
- Gather the proper supplies, including rubber or plastic gloves and a disinfectant or bleach solution made from a mixture of household bleach and water.
- Air out the space you will be cleaning for 30 minutes​.
- Spray the contaminated area with the disinfectant or bleach solution until very wet, and let it soak for at least 5 minutes.
- Wear gloves and use paper towels, a sponge, or mop to clean up the contaminated area.
- For more tips, tools, and information, visit https://www.cdph.ca.gov/Programs/CID/DCDC/pages/hantaviruspulmonarysyndrome.aspx
Rats bring in diseases, but roof and Norway rats have not been known to carry Hantavirus. Fleas from rats that bite humans can cause the plague, and there are other infectious diseases they can carry.
REMIDIATION OF RODENTS
Find the entry point that rats and mice are using, and seal them up. A mouse needs a very small hole about the size of your pinky finger or a dime, a rat needs a hole that its face can fit through, or the size of a quarter, and it will take care of the rest by knawing or squeezing. The key to not having rodents inside is to keep them outside.
Mice can be controlled with putting traps in the same place with the same methods, but rats don’t behave the same. The experts say one has to do prebaiting, and the rats become bait shy if you don’t provide enough, and we end up with animals that learn and have a higher intelligence level.
For rats, snap traps are best, and reuse them once one is caught. Other rats will smell the deceased rat and be attracted to the trap. They are tough to catch due to their intelligence, and this helps. .
Find out helpful information on the Centers for Disease Control website HERE.
There are different levels of rodents – you can’t give them places to live. Clean environments, seal up decks, seal up anything where they can get into your habitat, let them live in the woods.
If you find a mouse nest in a drawer, put it outside and let the sun and air get to it before cleaning.
Local exterminators are also the people to call if you’re not able to remediate yourself. It isn’t a one-and-done effort, and it requires a few trips to your home to check traps. They bait outside with secure bait stations so the rodents don’t get stuck inside the house.
Make sure you seal up your home – don’t want to be an open door for rodents. Now that the snow is melting and temperatures are rising, this may be easier to do at this time. Spring is a good time too since many rodents are mating.
People should not use poison, as the rodents carry it back to the nest or spread it through the area and come into contact with pets. Secondary poisoning is possible as predators can ingest the infected rodent and die themselves. The poison is a neurotoxin and can build up in a rodent’s system so anything that eats them will have resulting buildup as well.
The rodent issues at a home are on private property, so the homeowner’s responsibility. It is illegal to release trapped animals from your property. People may think more humane, but it is a death sentence anyway since taking it from a known environment to another, and it can just spread more easily to other areas.
California has implemented a ban on the sale and use of both first-generation and second-generation anticoagulant rodenticides (SGARs) through AB 2552 and AB 1788, aiming to protect wildlife from secondary poisoning. These had been successful in pest control, but the ban was created to protect wildlife, including mountain lions, birds of prey, and other animals, from secondary poisoning when they consume rodents that have been poisoned by anticoagulant rodenticides.
RATS AND PETS
Rats can be dangerous to dogs, posing risks of disease transmission, injury from bites, and secondary poisoning from consuming poisoned rats. They can also be dangerous for cats.
- Dog Disease Transmission:
- Leptospirosis: Rats carry the bacteria that cause leptospirosis, a potentially fatal disease that can cause liver and kidney damage in dogs. Dogs can contract it by coming into contact with contaminated urine or water.
- Rat-Bite Fever: Dogs can contract rat-bite fever through bites from infected rats, which can cause fever, chills, and muscle pain.
- Toxoplasmosis: Dogs can become infected with the protozoan organism Toxoplasma by eating rodents that have the Toxoplasmosis cysts developing in their muscles.
- Bubonic Plague: Dogs can become carriers of the Yersinia pestis bacterium if they are bitten by the flea of an infected rat.
- Salmonellosis: Dogs can become infected with salmonellosis by encountering the fecal material of rats.
While cats are predators, they can be fearful of large rats and may not always prey on them.
- Bites and Disease Transmission: Rats can bite cats, transmitting diseases through the rat’s saliva into the wound.
- Secondary Poisoning: If a cat eats a rat that has ingested poison, the cat can become poisoned itself.
- Toxoplasmosis: Cats can become infected with the protozoan organism Toxoplasma by eating rodents that have Toxoplasmosis cysts developing in their muscles.
- Intestinal Worms: Cats can become infected with roundworms by eating mice or rats infected with roundworm larvae.
- Size and Fear: While cats are predators, they can be fearful of large rats and may not always prey on them.
