Ants are the most commonly encountered insects within households, and several species are well known for establishing extensive infestations throughout large buildings like hospitals, nursing homes, restaurants, apartment complexes, and office buildings. Pest ants generally enter homes in order to seek out food sources and/or to secure cool and moist living conditions during bouts of excessively hot and dry weather. Most ant pest species are capable of establishing multiple indoor nests within dark, moist, and in many cases, inaccessible spaces, such as wall voids, ceiling voids, attics, behind cabinets, and some species are known to occasionally nest within cavities in structural wood.

There currently exists more than 13,000 documented ant species worldwide, with 270 ant species in California, only around a dozen of which are considered serious pests of homes and buildings. The most commonly controlled ant pest species within and around homes in southern California include invasive Argentine ants, Pharaoh ants, odorous house ants, pavement ants, southern fire ants, and thief ants. The notorious red-imported fire ant of the genus Solenopsis can only be found in certain localities in and around San Diego, and they are not believed to be present in Ventura County. However, the southern fire ant is a native species that also belongs to the Solenopsis genus, and they are very common in Ventura County.

While southern fire ants (S. xyloni) are not as aggressive as their invasive counterparts, the stings they inflict have been known to trigger serious allergic reactions including potentially fatal cases of anaphylactic shock. Southern fire ants nest in shallow soil beneath rocks and bundles of plant matter, and they often establish indoor nests within wall voids and behind baseboards. Thief ants (S. molesta) also belong to the Solenopsis genus, and although they nest in soil and exhibit behaviors similar to other fire ants, thief ants do not pose a sting hazard. However, the thief ant is one of only two ant species found on the Food and Drug Administration’s “dirty 22” list of common pests that contribute to food-borne illness. Along with another common ant pest in Ventura County, the Pharaoh ant, thief ants feed on dead rats and mice, and by doing so, they acquire pathogens that can wind up in the human foods these ants seek out within homes. At 1/32 of an inch in length, thief ant workers are small enough to slip into stored food packages, and they prefer greasy foods that are high in protein, but they will consume sweets as well. Thief ants are also known for nesting within pre-excavated cavities within structural wood.

Have you ever found ant pests within stored food packages in your home?

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