California Pest Information

Insect and pest infestations

Twin Home Services uses the most advanced chemicals on the market to ensure safe, effective treatment for your pest control needs. Our number one goal is to protect you, your family, and your home. If you have any concerns over the safety of your kids and/or pets, please contact our pest control technician today. We will be happy to answer all of your questions.
Twin has the knowledge and expertise to combat any pest or insect infestation in or around your home or place of business. These common California pests and insects may include the following:


Around 200 species of ants exist in California, but fewer than a dozen are important pests. The ants most likely to be found in and around your home are Argentine ants. Ants are social insects that live in large, underground colonies. Ants in the colony share a nest, and they divide important biological roles among individuals within the colony.

Ants are among the most prevalent pests in households. They are also found in outdoor areas and in other buildings where they can find food and water. Once ants have established a colony inside or near your home, they are often difficult to control. On plants (indoor and outdoor), ants assist production of certain other insects such as aphids, soft scales, whiteflies, and mealybugs, increasing damage caused by these pests. However, ants also perform useful functions, such as feeding on certain other pests, including fleas, caterpillars, termites, and dead insects.


Queen Argentine Ant

The Queen is recognizable by its wings and its larger size. Queens conduct the reproductive functions for the colony; they lay eggs and sometimes help feed and groom the larvae.


Worker Ant

Workers are female, sterile, and wingless. Workers gather food, feed and care for larvae, build tunnels, and defend the colony. (Male ants do not participate in colony activities; their only purpose is to mate with the queens.)


Although spiders are often unpopular, the venom of most species is not very toxic to humans, usually resulting in no more than a slight swelling, inflammation, or itching sensation. Most spiders’ fangs are too small or weak to puncture human skin. Spiders usually will not attempt to bite unless accidentally trapped against the skin or grasped.

Spider colors vary from dull gray, brown, and black to bright red, yellow, and green. Spiders have eight legs (four pairs) and two body regions: a cephalothorax (fused head and thorax) and an abdomen. Most spiders have six or eight eyes in various arrangements. All have a pair of jaw-like structures, the chelicerae, which end in a hollow fangs. The tip of the abdomen has a group of small fingerlike spinnerets that produce silk. Young spiders (spiderlings) resemble adults except for their smaller size and coloration.


Black Widow

The black widow spider has a potent venom and is considered the most venomous spider in North America. However, black widows inject a only small dose of venom that rarely causes death. The adult female has a shiny, black abdomen with a characteristic red hourglass on the underside. Adult females are typically 1/2-inch to 1-1/2 inches long (when legs are spread). Adult males are harmless, about half the female’s size, with smaller bodies and longer legs.


Yellow Sac Spider

Sac spiders are thought to be responsible for most indoor spider bites to humans. Sac spider venom is cytotoxic, causing tissues at the bite site to die. However, sac spider venom is not very toxic, rarely causing severe symptoms. Yellow sac spiders are light yellow to pale yellowish green, sometimes with a orange-brown stripe on top of the abdomen. Adult females are typically is 1/4- to 3/8-inch long (body), with a leg span up to 1 inch. Males are more slender, with a slightly larger leg span.

Rats and Mice

Rats are among the most troublesome and damaging rodents in the United States. They consume and contaminate food, damage structures and property, and transmit parasites and diseases to other animals and humans. Rats live and thrive under a wide variety of climates and conditions; they are often found in and around homes and other buildings, farms, gardens, and open fields.

Two species of rats are common in California: the roof rat and the Norway rat. The Norway rat is more common in most area, although roof rats can be abundant near coastal areas.

The house mouse is also common in California. House mice are found in and around homes and commercial structures as well as in open fields and agricultural lands. House mice consume and contaminate food meant for humans, pets, and livestock. In addition, they cause considerable damage to structures and property, and they can transmit pathogens that cause diseases.


Roof Rat

Roof rats are slightly smaller than Norway rats. Unlike Norway rats, their tails are longer than their heads and bodies combined. The roof rat is an agile climber and often builds nests in walls, attics, vines, and trees.


House Mouse

House mice are small rodents with relatively large ears and small black eyes. They weigh about 1/2 ounce and usually are light brownish to gray in color. An adult is about 5 to 7 inches long, including the 3- to 4-inch tail.


Norway Rat

The Norway rat is both larger and heavier than the roof rat. Norway rats often build nests in burrows under buildings, low shrubs, or ground cover, in wood piles or junk piles, and in garbage dumps. When Norway rats invade buildings, they usually remain in the basement or ground floor.


Fleas are reddish brown to black, wingless parasites that feed directly on humans, pets, or animals. A flea can jump 7 to 8 inches vertically and 14 to 16 inches horizontally. Cat fleas are frequently encountered in homes and are common on domestic cats and dogs. Dog fleas look like cat fleas, but are rare in California.


Adult Fleas

Adult fleas are very small insects (up to 1/8 inch). It can be difficult to see their distinguishing characteristics due to their size. Fleas are compressed from side to side so that they look like they are walking “on edge.” They have piercing-sucking mouthparts through which they obtain blood meals from their hosts.

Bees and Wasps

Bees and wasps are stinging insects in the order Hymenoptera. Their stingers are modified egg-laying apparatuses, so only females can sting. Social wasps, honey bees, and bumble bees live in colonies. Individuals in the colony are responsible for defending the nest. If the nest is disturbed, these individuals will defend it by stinging. Foraging members of the colony will also sting if they are disturbed or injured.

Two distinct types of social wasps are found in the western states: paper wasps and yellowjackets. Paper wasps are less defensive than yellowjackets and rarely sting humans. Yellowjackets are much more liable to attack than other types of bees and wasps.


Honey Bees

Honey bees are characterized by a long, pointed tongue, social habit, front wings with three closed submarginal cells, and no spurs at the tips of the hind leg. Honey bees are more brownish and fuzzier than yellowjackets, with less well-defined black bands. Adults consist of queens (3/5- to 3/4-inch long), which are fully developed egg-layers; drones (3/4- to 5/8-inch long), which are the functional males; and workers (2/5- to 3/5-inch long), which are undeveloped females.



The term yellowjacket refers to 8 species of wasps, including the western yellowjacket, which is the most commonly encountered species, and the German yellowjacket, which is becoming more common in urban areas of California. Yellowjackets are typically medium sized with jagged bands of black and bright yellow on the abdomen. They have a very short, narrow waist where the thorax attaches to the abdomen.


Bumble Bees

Bumblebees are large, hairy insects with a lazy buzz and clumsy, bumbling flight. Most bumblebees are black and yellow. Female bumblebees can sting. Since their stingers are not barbed like that of a honeybee, they can sting more than once.


Silverfish live and develop in damp, cool places, particularly in basements and laundry rooms. Silverfish hide during the day and come out at night to seek food and water. They feed on cereals, moist wheat flour, books, any paper with glue or paste (including wallpaper and book bindings), and starch in clothing. Scales found around or under damaged material is a good indication that these pests are present.



Silverfish are shiny, silver or pearl gray soft-bodied insects 1/3 to 1/2 inch long. They have scaly bodies that taper gradually to the rear with two slender antennae in front and three long, thin appendages in back.


Cockroaches commonly congregate in open spaces. Indoors, they are often found in dark, moist areas such as basements and crawl spaces. Other comman areas include bathtubs, floor drains, and sewers. Outdoor habitats include moist, shady areas such as yards, hollow trees, woodpiles, and mulch. Occasionally they can be found under roof shingles or in attics. Cockroaches live outside, but will wander indoors in search for food and water. They contaminate food and eating utensils, destroy fabric and paper products, and impart stains and unpleasant odors to surfaces they contact. They may transmit bacteria that cause food poisoning.



Cockroaches are medium-sized to large insects. They are broad and flat, with long antennae and a prominent, shield-shaped section behind the head. Adult cockroaches have membranous wings and lack the thick, hardened forewings of beetles. Cockroaches are nocturnal and tend to scatter when disturbed.