top of page
Two ants eating mealworms

Pest Library

Your Ultimate Guide To Common Household Pests In California

There is a large number of insects and rodents that can be found invading homes and businesses in Southern California. Not only can these pests cause costly damages to your property, but they may also threaten the health of you and your family. To learn more about the most common household pests that frequently invade our properties, use this reference guide!

American Cockroaches

The American cockroach is the largest house-invading cockroach species living in the U.S. Most adults grow to between 1-1/2 and 2 inches in length, but they do have the potential to grow up to 3 inches. American cockroaches are winged and can fly short distances. They are dark reddish-brown, with a lighter color outlining their bodies. Their most unique feature is a yellowish figure-8 pattern behind their heads. These roaches are scavengers and feed on decaying matter.

American Cockroach

American cockroaches prefer to live outside in diverse environments like under mulch, on tree bark, in city dumps, in steam tunnels, and in sewers. Their choice of moisture-rich nesting spots is why they are often called “water bugs.” These cockroaches commonly find their way inside homes and businesses, where they take up residence in damp, moist areas like basements, crawlspaces, and bathrooms. American roaches are dangerous pests because of the wide variety of parasites, bacteria, and human pathogens they are capable of spreading.

To prevent American cockroaches from invading your property, control moisture issues in and around your home, and eliminate as many entry points as possible. Fix leaky pipes and fixtures, place a dehumidifier in the basement, and utilize air conditioners. Trim back tree branches, overgrown shrubs, and bushes from the foundation. Keep locking lids on outdoor trash cans and compost bins, and maintain outdoor eating areas.


Ants are social insects that live and work together. They are a common household invader. All ants have three distinct body regions: a head, thorax, and abdomen; six legs; and a pair of antennae. The reproductive members of the colony are the only members that are winged. In our area, one of the most common species of ants is the Argentine ant. They are a small species that live together in extremely large colonies. Argentine ants are shiny and dark brown or black in color. Argentine ants are commonly identified by the well-defined trails they create between their nesting sites and food sources. Additionally, Argentine ants emit a musty smell after they are crushed.

Ant carrying food

Ants are a difficult pest to control, because they tend to invade businesses and homes in large numbers and, more often than not, have multiple nesting sites. They nest in the ground, under mulch, under fallen trees, in tree trunks, and under organic debris. Argentine ants like to nest in areas of very moist soil. Once on your property, they will find their way into your home to forage for food. It is not a matter of if, but when! Once inside, they may decide to stay and nest near their newfound food sources. Common indoor nesting spots include behind walls, under floors, above ceilings, near leaky plumbing pipes, and areas behind furnaces and other heating elements.

To prevent ants away from your property, remove fallen trees, tree stumps, piles of leaves, and other debris from your property. Create a barrier between any mulch or soil and your home's foundation. Trim back overgrown vegetation away from the exterior of your home. Make sure outdoor eating areas are kept tidy. Place locking lids on outdoor trash cans and compost bins. To keep ants from finding their way into your home, seal cracks in the foundation, exterior walls, and roof line. Place door sweeps on all exterior doors, and make sure screens are completely intact. It is also a good idea to place mesh covers over all vents, and seal spaces around utilities entering into your home.

Bed Bugs

Bed bugs are parasitic pests that feed on the blood of mammals. Unfortunately, humans are their preferred host. Bed bugs are commonly found wherever there are people, including homes, hotels, libraries, shopping centers, schools, and movie theaters. Adult bed bugs are wingless. They are about 1/4 of an inch long, have 6 legs, and have flat, oval-shaped bodies that are reddish-brown in color. After consuming a blood-meal, their appearance changes slightly, they turn darker in color and their body expands.

bed bug on window

Bed bugs are wingless, and therefore don't fly, but don't underestimate the agility of these apple seed-shaped pests. Without detection, bed bugs will easily crawl onto people or their belongings, hitchhiking their way into a new location. Typically, bed bugs will first invade sleeping areas, hiding in the seams of, or underneath, mattresses and box springs. However, if the infestation remains unnoticed, and as their numbers grow, bed bugs will travel throughout your home, invading multiple areas. Bed bugs are a difficult pest to control without professional help. Every single adult, nymph, and egg needs to be found and treated to prevent a re-infestation from occurring.


To prevent bed bugs from invading your property, keep bags, luggage, coats, and other personal belongings off the ground in public places, and away from other people's belongings. Always inspect your hotel room or any other type of vacation rental before bringing luggage and personal belongings into it. Do not purchase used furniture, mattresses, or box springs for use inside your home. Place a protective cover that encases mattresses and box springs to help reduce hiding spots in your home. Regularly vacuum your home. Immediately wash and dry newly purchased clothing on the highest heat setting the fabrics can handle.

German Cockroaches

The German cockroach is a very common species of cockroach. They prefer living indoors and are problematic inside homes, restaurants, and other facilities where food is present. The German cockroach has a flat, oval-shaped body, and is light brown or tan in color. They have two black stripes running horizontally down behind their heads. German cockroaches have wings but rarely use them. They are prolific breeders, and can quickly overtake any home or business they find their way into.

german cockroach lay on flower

German cockroaches are small, which allows them to easily enter homes and businesses unnoticed in bags, boxes, or packages. They also make their way indoors through small cracks and crevices in exterior walls and foundations. Once inside, they will easily move throughout a structure using wires, pipes, and wall voids as their own personal highway system. They nest in warm, humid, secluded places located near food sources. They are a dangerous pest to be nesting inside near people. This cockroach carries a wide variety of bacteria, viruses, human pathogens, and parasites on their legs and body that can make people ill.


To prevent these pests from invading your property, reduce moisture levels by repairing leaky pipes and fixtures, make sure crawlspaces are properly ventilated, and use dehumidifiers to lower moisture levels. Seal gaps in your home's foundation, exterior walls, and around utilities. Replace torn window screens. Keep lids on trash cans, keep all food in the refrigerator or in containers with air-tight lids, and regularly vacuum and wipe down counters.


Rats are rodents, and they are common invaders of homes and businesses. Rodents live and thrive in suburban, urban, and rural areas, taking advantage of any food or shelter sources they can find. Like all other rodents, rats have large, sharp front incisors. These incisors are continuously growing, and rodents constantly need to chew on hard objects in order to prevent them from overgrowing. This habit causes rats to be very destructive pests.

side view of a brown rat

In addition to being destructive, they are also very dangerous because of the number of diseases and bacteria they are capable of spreading to people. Rats have bodies that are covered in light brown to black fur. Their ears and scaly tails are typically void of hair.

In nature, rats live and nest in a variety of locations, including shrubs, trees, and dense vegetation. Some species create burrows under foundations, in woodpiles, in gardens, or underneath construction debris. Rats make their way inside of structures, foraging for food or safe, secluded shelter. Inside, rats nest in attics, basements, behind wall voids, or in crawlspaces.


To prevent rats from invading your property, inspect the exterior of your home, and seal any openings found in the exterior walls, foundation, or roofline. Trim back tree limbs, shrubs, and bushes from the exterior of your home. Make sure all outdoor trash cans and compost bins have tight-fitting lids on them. Place garden areas, wood piles, and compost piles a distance away from the exterior of your home, and remove piles of excess debris from your property.


Spiders are a type of arachnid. All spiders have 2 body regions, eight legs, and fangs (chelicerae), and do not have wings or antennae. Spiders are a predatory species and are environmentally important. They aid in the natural control of insect populations.


Most spiders that we come across and that find their way into our homes, are nuisance spiders and pose no real danger to people. However, in our area, dangerous black widow spiders are present and need to be avoided. Black widow spiders are shiny and black in color and are most often identified by a red hourglass-shaped mark located on the underside of their abdomens. Their venom is strong enough to cause health problems in people.

A large spider

These pests usually prefer to live outside in secluded areas. Common spots where spiders build webs include shrubs and bushes, gardens, wood or rock piles, and in the ground. Spiders often find their way inside to pursue their prey, or if the weather becomes too hot, dry, or wet. Once inside, they can be difficult pests to find and completely eliminate. Spiders inside your home or business hide in hard-to-reach, secluded areas. Closets, basements, attics, crawlspaces, and spaces under beds and furniture are common spider hideouts.

To prevent these pests from invading your property, remove wood piles, rock piles, and other debris from your property. Keep your lawn cut short, and cut back tree branches, bushes, and shrubs away from your home. Place garden areas a distance away from the outside of your home. Seal all openings leading into your home. Make sure all windows and doors have intact screens. Eliminate water sources by making sure gutters are clear of debris, and repair leaky hoses or fixtures. Inside your home, keep storage areas organized and free of clutter.

For professional residential pest control solutions in the Greater Riverside area and commercial pest control solutions in Riverside County, California, reach out to Pest Assassin today!

"Nathan has been handling our pest control needs for several years now. He is quick, honest, and reliable. We trust our tenants and owners with his services and will always recommend him to anyone in need of pest control. Thank you, Nathan!"

- First Choice Property Management

bottom of page