Insect and pest infestations
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.
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.
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.
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.
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.
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.
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.