Many of the rodents, especially the commensal rodents, are cryptobiotic animals. This means they possess a biology and behaviors that are secretive. Rats and mice are active at night, utilize secluded, hidden, or inaccessible areas as harborages, and are attracted to dark or shadowy areas during active periods.
Additionally, the cryptobiotic nature of the pests is accentuated by their quick movements in response to possible danger and their habit of remaining close to their harborage. Rodents quickly scurry for the nearest cover when they detect vibration or movements which enable them to often escape capture or detection. It is common for clients to state that they thought they saw something scurry out of the corner of their eye, but when they looked, it was gone.
Thus, rodents often remain undetected by people until their numbers increase. It is this cryptobiotic behavior that is responsible for the public to often perceive that these pests seemingly appeared from out of nowhere. Examples of other cryptobiotic pests in urban areas include bats, cockroaches, carpenter ants, silverfish, and termites.
Other Names: Common House Mouse and Domestic House Mouse.
Whiskers are located on the face with guard hairs on the sides and back to help with poor eyesight. It guides them to stay safely against walls, under objects, and in burrows. Whiskers are also used to detect motion and test surfaces, e.g., glue traps, before stepping on them.
Hantavirus is one of the greatest health concerns associated with mouse droppings. The virus lives inside mice feces and when disturbed can become airborne. Humans that inhale the disease are most at risk for transmission. During the cleaning process, every effort should be made to prevent stirring up harmful dusts.
Mice can survive an 8-foot fall onto a hard surface. A mouse can travel up to about 12 feet per second.
Food Preferences and Consumption
Omnivores. Seeds (preferred food), cereal grains, fruits, vegetables, and meats. Mice frequent many feeding sites – often 20 to 30 – during their active period, eating small amounts of food from each site. Daily consumption: 1/10 ounce. Water is not essential to survival if food contains at least 16 percent moisture.
Excellent climbers. Can be found in cultivated fields and other outdoor environments. Can also be found at or below ground level and in attics. Mice explore their territory daily in search of food. Nocturnal. Most activity and feeding takes place between a half hour after sunset and a half hour before sunrise. Strong social hierarchy. Able to swim. Can easily “jump” up to feed on bait in a vertically oriented bait station.
Other Names: Brown Rat, Gray Rat, Common Rat, House Rat, Wharf Rat, Sewer Rat, Barn Rat and Water Rat.
brown. Belly is lighter.
Whiskers on the face and guard hairs on the sides and back help an animal with poor eyesight stay safely against walls, under objects, and in burrows. Whiskers are also used to detect motion and test surfaces, e.g., glue traps, before stepping on them.
Droppings have blunt ends and are about 3/4 inch (2 cm) or less in length. Fresh droppings are soft and dark in color. A Norway rat averages 40 to 50 droppings per day.
Food Preferences and Consumption
Omnivores. Meats, fish, flour, cereal grains, fruits and vegetables. Eats almost any human food. Rats visit fewer food sites than mice, but eat more at each site. Consumes 3/4 to 1 ounce of food each day. Requires water daily to survive – drinks 1/2 to 1 ounce of water daily.
Norway rats burrow extensively in soil and are excellent swimmers and good climbers. They usually nest in basements and lower portions of buildings. Nocturnal. Most activity and feeding takes place between a half hour after sunset and a half hour before sunrise. Very strong social hierarchy – the biggest and strongest Norway rats get the best food and harborage.
Food Preferences and Consumption
Omnivores. Seeds, fruits, vegetables, eggs and grain. Rats visit fewer food sites than mice, but eat more at each site. Consumes 1/2 to 1 ounce of food daily. Drinks up to 2 ounces of water daily.
Rats (indeed all rodents) prefer harborage as close to food as possible. However, if necessary they will travel several hundred feet from good harborage to good food. Rats have been known to survive a fall from 25 feet to a hard surface. Rats can and do enter buildings by swimming up through a toilet. Dry drains and toilets are even easier routes of entry for rats coming from a sewer system.
Other Names: Alexandrian Rat, Black Rat, Fruit Rat, and Ship Rat.
Food Preferences and Consumption
Omnivores. Seeds, fruits, vegetables, eggs, and grain. Rats visit fewer food sites than mice but eat more at each site. Consumes 1/2 to 1 ounce of food daily. Drinks up to 2 ounces of water daily.
Able to swing, jump and climb, roof rats usually enter and nest in upper portions of buildings. May nest outside in trees (especially palm), ivy and similar vegetation. Burrow very little. Nocturnal. Most activity and feeding takes place between a half hour after sunset and a half hour before sunrise. Strong social hierarchy.
The Trouble With Commensal Rodents
Commensal is defined as “sharing one’s table.” Commensal rodents, which include Norway rats, roof rats and house mice, live off humans without returning anything of worth. What they do return is the potential for serious problems.
Spread serious diseases, including salmonellosis (food poisoning), leptospirosis, rickettsialpox and lymphocytic choriomeningitis (LCM).
Carry fleas, ticks and other ectoparasites, which potentially spread other diseases, such as bubonic plague.
Consume or contaminate about 20 percent of the world’s food supply.
Gnaw, causing expensive structural damage. They also can start fires if they gnaw on electrical wires.
Cause a great deal of anxiety for occupants (people and pets) of infested buildings.
Pose serious risks for food facilities. Even a single rodent can cause serious problems for a food facility including fines, poor inspection scores, disgruntled employees and lost business
Mice and rats reproduce rapidly, as is generally the case with small prey animals. Their relatively short life spans, short gestational periods and rapid sexual maturity make effective rodent control critical. The reproductive cycle and number of rodent offspring increases with adequate food, water and harborage.
House Mouse Reproduction Cycle
Mice become sexually mature and able to mate in as little as 5 weeks. Generally, sexual maturity is reached in 5 to 8 weeks.
Female mice reproduce up to 8 times in their lifespan, with litters averaging 4 to 7 pups. Therefore, a single female may produce up to 56 offspring annually.
Rat Reproduction Cycle
Norway and roof rats become sexually mature and able to mate at 8 to 12 weeks of age.
Norway rats average 8 to 12 pups per litter, averaging 4 to 7 litters per year.
Roof rats average 4 to 8 pups per litter, averaging 4 to 6 litters per year.
Related Reproductive Traits & Characteristics
House mice, Norway rats and roof rats share several reproductive characteristics:
After giving birth, they can be in heat and become pregnant again in as little as 24 to 48 hours.
Females can be pregnant and still lactate to feed their current litter of pups. However, the gestational period may be slightly longer in this case.
They will reproduce year-round in stable environments with adequate food, water and harborage. Less favorable conditions limit reproduction to spring and autumn.
Research has found, most rats and mice do not survive a year in the wild. Predation, disease, starvation, cannibalism and rodent control professionals all take their toll.
The Inspection Process
Rodents usually behave predictably. A rodent control expert is a detective searching for clues that point to an infestation. This knowledge is then used to choose appropriate rodent control tools and techniques, and know when to use them.
Interview customers for information about rodent sightings and sounds.
Perform a thorough inspection, beginning with the exterior premises, if appropriate.
Think three-dimensionally, looking both high and low. Rodents have been known to climb 30 feet to gain access to a structure, roof rats even more.
Identify interior and exterior problem areas including: runways, nests, feeding sites, water supplies, vents and other openings, burrows, harborages, pipe outlets and inlets, and holes or cracks in the structure.
Check all dark areas with a flashlight
Flashlight (with a strong beam) to find rodents and their signs in dark areas.
Black light to identify rodent urine.
Knife, palette knife, or spatula to test age of droppings and to scrape droppings out from under objects for identification.
Knee pads to protect your knees from sharp objects on floors and in crawl spaces.
Specimen container to collect unknown specimens.
Prevent infestations by changing the physical conditions of the building through exclusion and sanitation.
The best way to keep buildings rodent free is to prevent rats and mice from getting inside. Rodents fit through tiny openings and can gnaw through wood, lead, aluminum, copper, cinder block and uncured concrete. Mice can squeeze through gaps larger than 3/8 inch by about 1/2 inch and mature rats need an opening at least 3/4 inch in diameter. Juveniles may be able to fit through a smaller opening. They will enlarge openings that are too small by gnawing it big enough for their body to fit through. The following measures, with the proper materials, will make buildings less accessible to rodents:
Patch openings in walls larger than 1/4 inch using gnaw-proof materials, such as steel sheeting, 1/4 inch hardware cloth, galvanized steel and concrete. Holes may be plugged with steel wool or copper mesh prior to patching.
Seal gaps under siding at the top of the foundation.
Close outside doors tightly when not in use.
Install tight-fitting weather stripping on the bottom of all pedestrian doors and overhead doors.
Cover all air vents with 1/4 inch hardware cloth. Make sure dryer vent “flaps” are working properly.
Hand sanitizer (over 62% alcohol) to kill bacteria when soap and water are not available.
Binoculars to make it easier to see what you can’t get close to.
Eliminate water sources available to rodents.
Eliminating places that may provide rodents with shelter, water and food is the purpose of sanitation.
Eliminate debris in and around buildings and grounds.
Trim weeds and brush and keep grass short (3 inches or less) to minimize cover and food sources around the building perimeter.
Clean up food waste and spillage daily.
Store food 12 to 15 inches off the floor and 12 to 18 inches away from the wall for easy inspection and sanitation. Use rodent-proof containers when possible.
Allow 24 inch aisles between stored materials and walls for improved sanitation and inspection.
Screen dumpster drainage holes with hardware cloth.
Don’t leave pet food out overnight. Clean up dog droppings daily.
Clean up windfall fruits, nuts and bird feeder spillage daily.
Clipboard, graph paper and pencil to diagram building and take extensive notes.
Inspection checklist to act as a reminder to inspect critical areas.
Respirator with appropriate filter to prevent inhaling dust, which may be contaminated with disease organisms. Consult with your safety equipment supplier for current recommendations.
Store snap traps away from insecticides and chemicals that may impart a flavor. Remember, rodents have a keen sense of taste.
Bait snap traps with food that is more attractive than other readily available food sources, such as gumdrops, peanut butter, bacon, nutmeats or dried fruit (raisins).Secure bait to the snap trap trigger – a length of thread works well. For rats, fish (tuna) and meat (cat/dog food) may be used to bait traps. Glue boards can be baited, if necessary, with non-oily foods. The use of peanut butter, bacon and other oily, greasy foods will cause the glue to lose its stickiness.
Bait some mouse snap traps with nesting materials, such as cotton or dental floss, with a drop of vanilla. Mice constantly look for nesting material.
Liphatech’s Rat and Mouse AttractantTM is often readily accepted by both rats and mice when used as a lure on traps.
Place mechanical or snap traps and glue boards in areas unsuitable for rodenticide applications.
Position snap traps and glue boards to intercept rodents in runways. Place snap traps with the trigger toward the runway – generally along a wall, in corners, behind and under objects and near abundant tracks and droppings. Snap traps also may be attached to pipes and beams used as runways.
More traps are better than fewer traps.
Pre-bait traps until rodents, especially rats, overcome their fear and take bait readily. This may take several days for mature rats.
Glue boards shouldn’t be used in areas with excessive dust or wetness – both elements make glue boards ineffective.
Check glue boards frequently to prevent rodents from escaping.
For mice, repeating or automatic mechanical traps may be used. Watch for tracks in the dust on the top of low-profile traps, which indicate mice are running over the top of them.
Two primary types of rodenticide baits are available – non-anticoagulants (acute) and anticoagulants.Non-anticoagulants. Bromethalin, cholecalciferol (Vitamin D3) and zinc phosphide based products are examples of acute baits which have no antidote. Palatability is generally low with wax blocks containing these active ingredients.
Non-anticoagulants are considered single-feed baits because rodents typically stop feeding after one meal. If a lethal dose is ingested, rodents usually die within 24 hours. If a sub-lethal dose is eaten, rodents tend to develop bait shyness.
Anticoagulants. The preferred rodenticide type among rodent control professionals, anticoagulants inhibit the blood-clotting mechanism, causing rodents to die from internal bleeding. Some of these rodenticides are singlefeed and effective within several days. The delayed effects of anti-coagulants help reduce bait shyness.
The antidote to human or non-target animal poisoning is Vitamin K1.