Liometopum occidentale
Liometopum occidentale, also called the velvety tree ant, is a species of ant in the subfamily Dolichoderinae. "Liometopum occidentale" is often mistaken for carpenter ants ("Camponotus" spp.) by homeowners and pest management professionals. This mistaken identity is due to morphological and behavioral characteristics they share with carpenter ants; namely polymorphic workers, a smooth convex thoracic profile, and the tendency to excavate wood. Consequently, their importance as structural pests may be greatly under reported, especially in California, Oregon, and Washington, United States. Taxonomy. "Liometopum occidentale" was originally described as "Liometopum microcephalum" var. "occidentale" by . relocated it to a variety  of "Liometopum apiculatum". It was finally elevated to the species level by and remained there in a recent taxonomic review by Del Toro et al. (2009). Habitat. "Liometopum occidentale" is found from sea level to over 1840 m in coastal regions from southern Washington to northern Mexico. The range of elevation of this species also appears to depend on latitude with ants collected from locations in Oregon as low as 7 m and up to 1700 m in California. They are the most common and dominant ant in oak and pine forests of southwestern U.S. They prefer to nest in  the crevices of oaks, alders, elms, cottonwoods, and creosote, in soil, underneath bark of dead trees. Colonies. After finding no aggression between workers collected from significant distances apart and no territorial boundary, speculated that "L. occidentale" colonies are large and polydomous. Since they never found brood or queens, it is uncertain whether there are multiple queens within a nest, or whether each queen has some localized "sphere of exclusivity." and it just seems unlikely that there could be just one queen that produces enough eggs to establish a colony that is one kilometer wide, they also speculated that "L. occidentale  are polygyne. Colonies have been estimated to contain between 40,000 and 60,000 workers. Colony foundation of this species has not been studied as well as it has with the other two North American species. Nests. Liometopum occidentale" typically nest in soil, crevices of trees, and under the bark of dead trees. However, were never found by leading to the speculation nests must lie deep under large boulders or among roots of large trees. To better understand the structure of their nests, more nests need to be excavated. Feeding. "Liometopum occidentale" are opportunistic omnivores and can often be found tending hemipterans  and carrying prey insects back to the nest. They readily attend hemipterans and are found in citrus groves, but their role in disrupting biological control has not been determined. Their feeding preferences need to be studied to enable the development of an effective bait for pest control purposes. Foraging activity. "Liometopum occidentale" form massive foraging trails that extend 60 m or more from the nest, and can even be observed on hot days with temperatures between 24 and 38 °C. observed "L. occidentale" traveling mostly underground in very shallow galleries (1–2 cm deep), or in leaf litter, however, we  have also observed massive above ground trails. According to , "L. occidentale" in natural environments forage an areas as large as 2,000 m, but they only utilize between 486 and 1198 m (740 m average) of this area at any one time. This means that they are only using between 33 and 68% of this area, more than twice that of "L. apiculatum". Reproduction. Nuptial flight of "L. occidentale" reproductives have been observed throughout May. The annual productivity for a colony (40,000 to 60,000 workers) of this species is 2 to 2.8 kg of brood per year for 4–8 years. Workers  housed without a queen will also lay unfertilized eggs that are eaten or develop into males.