Recent years have brought a new surge of rat infestations in some major American cities. In 2016, USA Today reported increases in rat populations in New York, Chicago, Boston and Washington, DC, with the biggest increase noted in Chicago, where the rat population is increasing on average by 70% a year. That same year, New York received more than 41,000 complaints of rodent activity. And in Baltimore, residents in low-income areas where rats were prevalent were found to have higher rates of depression than residents of other parts of the city.
With statistics like these in mind, cities are bolstering the resources they’re deploying against rat infestations:
- Chicago is increasing the number of city-employed rodent technicians and experimenting with new ideas to help the Chicago Transit Authority reduce rats in public areas.
- Boston has started a 311 line specifically for reporting rats. The city has also worked with MIT and Harvard to test an approach using dry ice that seems, at least from initial reports, to be working.
- Cities are also cracking down on residents who contribute to the problem. Chicago fines homeowners up to $500 for leaving pet droppings or garbage in their yards, with other cities following suit. Some homeowners are unhappy about these efforts, but many are taking matters into their own hands rather than waiting on the city.
The Risk of Disease
Rats in public places are obviously a serious problem. But in the home, they’re actually an even bigger problem. For one thing, rats do not have to bite in order to cause illness; if you’re looking for reasons to get rid of rats in your home, then understand that mere exposure to rat waste is the cause of many debilitating diseases. Rat urine, for example, is one of the leading causes of leptospirosis, a condition that can cause severe kidney and liver damage among humans.
Other diseases that are specifically carried by rats include, but are not limited to:
- Salmonellosis – a disease that can cause abdominal cramps, diarrhea, intense vomiting and fever. Symptoms can begin as soon as 12 hours after exposure.
- Weil’s disease – a severe form of leptospirosis, caused by the same bacteria. If leptospirosis reaches this stage, you will likely have to be hospitalized. Severe reactions may occur in the lungs, the heart, and the brain, if the bacteria reaches those organs.
- Rat bite fever – a disease which can be passed to humans from rat urine or mucus. It is also known as epidemic arthritic erythema, streptobacillosis, streptobacillary fever, sodoku, and spirillary fever. Symptoms may include chills, fever and intense vomiting.
- The plague – which can be spread through airborne contact in extremely unsanitary areas. The bubonic plague, one of the longest- lasting rodent-borne diseases in the world, is only one manifestation of this disease.
- Hantavirus – a disease serious enough to require a report to the Centers for Disease Control and Prevention (CDC) if contracted. If it progresses to Hantavirus Pulmonary Syndrome, it can be fatal.
How to Tell Rats from Mice and Other Rodents
If you’re already going to get rid of rats in your home, then it may not matter to you that there is no official scientific difference between a rat and a mouse. But as it happens, many rodents identified as rats in a visual sense are actually not closely related at all. The term “rats” includes rodents as widely diverse as pack rats, naked mole rats, wood rats, cotton rats, Norway rats, roof rats, and kangaroo rats. At the same time, some species with different names, such as Norway rats and house mice, are both descended from a single ancestor.
Scientifically, rats are usually defined by the fact that they have more pairs of chromosomes than mice (22 to 20). Rats also generally develop more slowly than mice, with a gestation period of 24 days rather than 19 days. Most rats will also have more nipples than mice or other rodents.
The general consensus on the definition of rats includes one essential thing: size. If a rodent seems large in comparison to other similar looking rodents in its geographical area, it is considered a rat, and this is true of Norway rats and roof rats, the two most common house invaders. Rats also generally have larger feet and ears, with large, chunky heads.
Identifying Types of Rats
The industry for rats as pets has done a great deal to help people classify the different types of wild rats that infest major metropolitan areas. Although the distinctions are not scientific, the descriptions may help you determine the type of rat that you see around your property.
The rat body type corresponds to 4 different distinctions.
- Standard – This is the most common body type and usually corresponds to wild looking, large ears on a rodent.
- Dumbo – The ears on a dumbo rat are larger than the Standard type, and they are also set much lower on the head.
- Manx – Compared to the Standard body type, the Manx has a slimmer and smaller body overall.
- Dwarf – Considerably smaller than other rats, these are distinct from mice because of their longer tails and more pointed heads.
Rats also have different types of coats.
- Standard – This is the most common type of coat and looks typical, with straight fur.
- Rex – This coat has curly hair.
- Double Rex – A rat with a Double Rex coat type will also have curly whiskers alongside patchy hair.
- Hairless – This recessive trait is self-explanatory.
There are two basic colors for the color of the coat – agouti and black. Agouti is the dominant trait and usually corresponds to most wild rats. There are many modifiers that play off of this base coat, affecting the color that you see.
- Red eyed dilute – A rat with red eyes will turn an agouti coat a fawn color and a black coat tan.
- Pink eyed dilute – A rat with pink eyes will turn an agouti coat amber and a black coat mocha brown.
- Albino modifier – The rat will have pink eyes and a totally white coat regardless of the color of the base coat.
- Blue modifier – The rat’s coat will be silver or blue with tan tipped hairs if the base coat is agouti. A base black coat will come out all blue.
- Mink modifier – This will turn an agouti base reddish brown and a black coat gray.
- Pearl modifier – This will turn an agouti coat gold and silver and a black coat pearl.
The last modifier is a pattern modifier.
- Self – This is the most common modifier and does not change the look of the rat.
- Berkshire – This modifier gives the rat white feet and a white belly.
- Blazed – Blaze leaves a “blaze” on the face between the nose and eyes.
- Capped – The rat will only have color on its head area, with the rest of the body colored white.
- Hooded – The hood modifier gives a rat color on its shoulders and down the back as well as on its head.
- Irish – This type of rat is colored solid except for white paws and a single spot on the belly.
- Masked – This is a white colored rat with color only over the eyes.
- Roan – This rat type is born with a solid color that will fade as the rat gets older.
Inspecting Your House for Evidence of Rats
Regardless of their color, rats will leave distinctive signs of their presence in your house, although you may never see one. Here are some of the signs that you should look for if you think that you have a rat infestation. If you find any of these signs, you should take steps to get rid of rats in your home.
- Droppings. One of the most obvious signs of rat infestations, these are usually dark brown and will resemble a rice grain in shape.
- Unusual smudges along your walls. Rats will leave discolorations on the lower parts of walls as they rub against them. The color comes from the grease and dirt they drag in from outside.
- Scratching noises. If you hear scratching noises at night in your loft, you may have a black rat (also known as a roof rat) infestation. This particular species is very adept at crawling upwards.
- Rat holes. Brown rats have the ability to dig sophisticated burrows in order to nest, store food, and shelter themselves.
- Rat nests. If rats get into your attic or loft spaces, they may shred your insulation in order to make a nest.
- Footprints. You may find rat-sized foot marks in the less traveled areas of your home.
Rats usually find their way into places that provide feeding opportunities. The smell from your garbage may attract them, as will the odor from old food in your cupboard or even your refrigerator. Make sure that you always immediately throw out any food that is past its expiration date.
One thing that makes it hard to get rid of rats is our tendency to leave food lying around for them. Rats often find their way into places that provide feeding opportunities, and you may not realize the variety of food sources available in your home. For example, rats eat garbage, so the smell from your garbage cans can attract them, as can the odor from old food in your cupboard or even your refrigerator. Make sure that you always immediately throw out any food that is past its expiration date. Also keep an eye on pet food: remove any remaining food from open dishes once your pet has finished feeding, and store pet food in airtight containers.
You can also sanitize your home by regularly vacuuming and dusting. Many of the odors that draw rats come from dust and food droppings that find their ways into the corners of your home. Make sure that you move your furniture and get in the corners of your home to clean up all of the old food and sticky dust that may attract them.
It also helps to eat food only in specified areas. If your family frequently eats in bedrooms, food will inevitably fall behind headboards and under beds, attracting rats.
You also need to protect your home from your neighbors’ sanitation problems. If your neighbors are messy or smelly, you may want to have a talk with them. You can also protect your home by setting up a rat poison barrier around your own property.
Rat-Proofing Your House
- Start by inspecting the foundation of your home. Look for gaps or holes that may be large enough for a rat to enter. You can block off those entry points with foam or mesh.
- Once those areas are secured, check your doors and windows. This is especially important at the change of seasons, when doors and windows may warp and leave gaps that rodents can crawl into. Metal kick plates are a good solution for these, as well as insulation treatment.
- Next, inspect your roof. If your vents, shingles, or chimneys allow access to your attic, you may have a problem: roof rats can be especially difficult to eradicate once they’ve gotten into your attic. Cap the chimney when it is not being used, fix any holes in flashing or broken casings for vents, and make sure your roof is in good repair in general.
- Consider using a metal rodent guard if you have any wire lines or pipelines that come from the outside into the house. You can also block holes with a mixture of steel wool and mortar or caulk.
Treatment & Eradication
Traps are the best-known means for getting rats out of a home. But you have to use traps wisely in order to make them effective. Here are some trapping guidelines:
- Use a large number of traps.
- Make sure that you are using rat traps. Mouse traps are too small to trap rats.
- Place the traps in the most infested areas – dark corners, behind big appliances and wherever you see droppings. You can also put rat traps on tree limbs that overlap the house to prevent roof rat invasions—and put them in your attic as well.
There are also many types of rat traps to use:
- Snap traps/spring traps: These are the best known types of traps, and these days they come in two varieties—the old-fashioned trap (usually made of wood and steel wire) in which a spring-loaded bar snaps down when a rat removes bait from a trigger, and the newer version, usually made out of plastic, where a set of sharp jaws snap shut when triggered.
- Live traps: These traps consist of a cage with a spring-loaded door that captures a rat inside when they remove bait from a trigger or walk across a trigger plate.
- Glue traps: A type of live trap, glue traps consist of a plastic or wooden platform coated with adhesive that is laid out (and sometimes baited) in places where rats are known to travel (basements and pantries for Norway rats, attics and other high spaces for roof rats) in order to entice rats to get stuck on them. These tend not to be true live traps, as it is often impossible to remove a rat once it is trapped, and trapped rats will eventually die of dehydration. This also means that unlike most other traps, glue traps are single use.
- Electric/electronic traps: These traps work like cages, but when the bait entices rats to enter, these traps detect the rat and send a lethal electric shock into the cage.
What should I use as bait?
Most rodent traps require you to use some type of bait to attract rats to them. But much that is sold as “bait” is actually poison, so you may want to put some thought into the bait you use, especially since the bait on traps is often available to people and household pets. To bait a trap with non-toxic baits, you can use anything edible, but popular (and effective) baits include peanut butter, fresh fruit, and dried fruit.
Sometimes also referred to as bait, rat poisons come in a few varieties, mostly differing in their delivery method.
Bait stations: Usually made from hardened plastic, bait stations allow homeowners to place rat poisons in open spaces without having to worry about pets or other people accessing the poison. They are enclosed, with rat-sized openings to allow rodents to access the bait, and usually lock closed with a special key to make the poison even more difficult to access.
Bait trays: Bait trays usually come pre-prepared and can be purchased in hardware stores. They are not enclosed, however, so they should only be used in spaces inaccessible to pets or children.
Bait or poison pellets: These come in bait trays and can also be bought in bulk to refill trays or bait stations. Overall, the three main types of rat poison include:
- Bromethalin-based poisons: these fast-acting neurotoxins need, more than most poisons, to be kept out of the way of children and pets, but they are especially effective.
- Vitamin D-based poisons: These poisons (and similar ones based on other vitamins) induce a build up of fat-soluble vitamins that eventually lead to a fatal overdose. These are slower-acting, but can still present a danger to kids and household pets as well as rodents.
- Fumarin and warfarin-based poisons: these types of poisons act as anticoagulants, preventing rats’ blood from clotting. These are the slowest-acting poisons in general use, and can take repeated feeding to be effective.
One note about poisons: wherever you place them, rodents will feed off of them and then go elsewhere to die. Ideally you’ll be able to place them outside in order to prevent any rats from dying in the walls or the attic of your home.
When to Call a Professional
If your own efforts do not get rid of rats in your home, then it may be time to call in a professional pest control service. They will put the best rodent control practices and the best rodent control technology in service of ridding your house of rats and mice. Pay attention to the advice of your rat removal/rat control professional if he tells you that you have a worse problem than you think, because you probably do.