Ochetellus glaber (also known as the black household ant) is a species of ant native to Australia. A member of the genus Ochetellus in the subfamily Dolichoderinae, it was described by Austrian entomologist Gustav Mayr in 1862. Aside from Australia, O. glaber has been introduced to a number of countries, including China, India, Japan, New Zealand, the Philippines and the United States, where it has established itself in Hawaii and Florida. It has been found on Lord Howe Island, New Caledonia, Norfolk Island, Réunion, New Zealand, and the Solomon Islands. Compared with other ants, O. glaber is a small species, with workers measuring . Males are the smallest at , while the queens measure . The ant's colour ranges from brown to black.
Described as an arboreal nesting species, O. glaber lives in open or savannah woodland areas, nesting under stones, old dry logs, rotten wood, and in hollow trees and plant stems. Nests can also be constructed in buildings and structures, specifically in pavings, ceilings and walls. It is both diurnal and nocturnal, forming long trails from trees in search of food such as honeydew and insects. It has developed some associations with certain flowers and also tends to associate with some insects, such as mealybugs and aphids. During the nuptial flight, queens mate with either one or multiple males; males only mate with a single queen. Sometimes, a subset of a colony may leave the main colony for an alternative nest site as an act of dispersal. O. glaber often invades human homes to feed on household foods, and is considered a household pest. It has been intercepted numerous times in the United States, where it has the potential to disrupt the biological control of certain pests and cause long-term ecological impacts in areas where it is not native.
Taxonomy
Ochetellus glaber was originally described as Hypoclinea glabra by Austrian entomologist Gustav Mayr in his "Myrmecologische studien" in 1862. The ant was described from syntype workers and males Mayr collected from Sydney, Australia, now preserved in the Natural History Museum, London. Its placement in Hypoclinea was relatively short, as Mayr transferred it to the genus Iridomyrmex as Iridomyrmex glaber in 1865. Its placement in Iridomyrmex was accepted for more than a century, until entomologist Steve Shattuck revised the genus in 1992 and transferred the ant into a new genus, Ochetellus. He also designated O. glaber as the type species of the genus. In 2011, evidence emerged that O. glaber represents a species complex, indicating that the current taxa may need to be split.
O. glaber has two synonyms, Iridomyrmex itoi and Iridomyrmex itoi abbotti. I. itoi was described as a separate species, while I. itoi abbotti was recognised as a subspecies. The subspecies was short-lived, and was synonymised with I. itoi in 1910, and in the 1950s I. itoi was first noted to be similar to O. glaber. Despite the similarities, I. itoi remained a valid species until a 1995 publication confirmed its synonymy with O. glaber. It is commonly known as the black house ant or the tramp ant.
Description
O. glaber is small, with workers measuring . The antenna has 12 segments, the scapes of which are half as long as the head. Its antennal sockets and posterior clypeal margin are separated from one another by a small distance, perhaps less than the minimum width of the antennal scapes. Eyes range in size, being either medium to large, with more than six facets (lenses that make up the compound eye of an insect). The dorsum of the mesosoma has distinct metanotal grooves and lack erect hairs. The propodeum has a distinct protrusion which causes the slope to be strongly concave. The ant's waist has only one segment. The petiole (the narrow waist) is upright and is not flattened. The gaster has a ventral slit. Constriction between the third and fourth abdominal segment is not visible. The ant's colour ranges from brown to black. Males are smaller than the workers, measuring . The body is brown in colour, but the back of the body is brownish-black, and the mandibles, legs and antennae are yellow. The head and thorax are noticeably wrinkled. O. glaber queens are larger than the males and workers, measuring .