Rodents are small animals that belong to the family Rodentia. Rodents are the largest group of mammals. Among the many species are squirrels, chipmunks, rabbits, hamsters, guinea pigs, rats and mice. Rodents generally have a very high reproductive capability, and they have a very important role in the ecology of the earth. Rodents are the largest component of the food chain for higher vertebrates such as foxes, wolves, cats, hawks, owls, etc.


Although they may appear cute and fuzzy to some people, many rodents can be a significant pest problem. Rats and mice contaminate food products, food production equipment and storage areas, damage stored items, and have even caused electrical fires by gnawing through wiring.


Fleas and other parasites of rats and mice are the cause of countless human deaths and diseases. The so called “Black Death” of Europe killed 25 million people in the five years between 1347 and 1352. Approximately 1/3 of the population of Europe was wiped out. The disease, bubonic plague, is carried by rats and spread to humans by their fleas. Today, plague is still a problem. It is present in ground squirrel populations right here in the San Joaquin Valley.

Commensal Rodents


Commensal rodents are those species that will live in close association with people. Typically when we speak of commensal rodents we are talking about rats and mice.

House Mouse

Mus musculus


House MouseHouse mice are distributed all over the world. Like many pest species, they are not native to the United States, but have been introduced accidentally at many of our major seaports.


House mice are highly active at night, but may also display some activity during the daylight hours. They are inquisitive and will quickly investigate any new object placed in their normal foraging territory.


These little rodents have a terrific reproductive capacity. A single female can produce as many as 13 litters in a year with usually six young per litter. That adds up to 78 babies per year per female!


They will eat almost anything that we will eat. They are especially troublesome to homeowners when they invade a kitchen or pantry area. We often find evidence of house mouse activity in garages and storage buildings.

Deer Mouse

Peromyscus spp


Deer MouseUnlike the introduced house mouse, the deer mouse is a native to the United States. There are several species scattered throughout the country. Deer mice are not common in the Fresno area but may be found in the nearby foothill and mountain communities. Like most mice, the deer mouse is largely nocturnal in its habits, although they may display some foraging during the daytime hours.


The white footed deer mouse has been associated with the spread of Hantavirus and some other diseases.

Brown Rat

(Aka Roof Rat, Black Rat, Fruit Rat, Tree Rat)
Rattus rattus


Brown RatThe brown rat is the most common rat species in the central San Joaquin Valley. (Other parts of the country are more troubled with the Norway rat discussed below.) The brown rat is a very agile climber and may be found in trees, roof-tops, and running along power lines. They will feed on a wide range of food items and are especially fond of the fruit and nuts found growing freely in many of our back yards.


Like most other rodents, brown rats are primarily nocturnal in their habits. They tend to sleep during the daytime hours and conduct most of their business of survival after dark. If the rats have found a way to get into the attic of a home, their nighttime activities can become very annoying.

Norway Rats

Rattus norvegicus


Norway RatsThe Norway rat is a much heavier and more solidly built animal than the roof rat. Norway rats are not good climbers, preferring instead to burrow into the ground under rocks, in ditch-banks, and sometimes even under buildings. Norway rats are excellent swimmers and are found in the sewer systems of some major cities.


Norway rats are rarely found in the rural areas of the central San Joaquin Valley. These rats are much more commonly found in the older areas of many of the valley’s cities. I have encountered Norway rats in most of the areas of central Fresno. They are well established in the older industrial areas, especially in the vicinity of old ditch-banks and industrial ponding basins.

Rodent Control


Generally speaking, rats and mice don’t pose a significant problem as Rodent Controllong as they remain outdoors. And as a pest control company, there is little, if anything, we can do to control a neighborhood-wide rodent problem. That work falls within the scope of the community’s health department. Rats or mice inside the home are a different matter.


Most of the calls we get for rat control are triggered by noises in the attic or walls at night, and/or evidence of rats in the garage or storage areas. Our contract for regular pest control services includes service to control rats and mice.


Rodent control begins with an inspection of the property. We will try to figure out how the rodents are gaining access to the interior areas. Locating and sealing up the rodent entry points is critical to achieving any decent level of control. If the entries are closed off, any attempts at baiting or trapping will do nothing more than “harvest” the rodents as new ones find their way in.


Once we have found as many entries as we can locate and our customer has taken steps to close them up, all that remains is elimination of the rodents in the structure. This can be accomplished by baiting or trapping.


It is important to keep in mind that rodents may want to get past our efforts to keep them out. They can create new openings into the building or find others that we might have overlooked. Rodent control is not a “do it once and forget it” kind of a job. If you live in an area where rodents have been a problem, you need to keep a watchful eye for new signs of rodent activity and further maintenance may be required.

Other Rodent Problems


Gophers, ground squirrels and rabbits can be serious pest problems when they occur in large numbers and those numbers impact our lives. As a structural pest control company we do not provide services to control these pests. Services to control ground squirrels and gophers are usually provided by companies that are licensed by the State Agriculture Department rather than the Structural Pest Control Board. Refer to our Helpful Links page for further information.

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