Pest Profile

Photo credit: April Nobile, California Academy of Sciences (Specimen: 0005328; from https://www.antweb.org

Common Name: Velvety tree (California velvety tree ant)

Scientific Name: occidentale

Order and Family: Order ; Family Formicidae

Size and Appearance:

Length (mm) Appearance Egg

Larva/Nymph

Adult Workers Workers are polymorphic and covered by fine hairs, which range from gives them a velvety appearance. The workers are bicolored 2.5 – 6 mm with a darker head and abdomen and lighter thorax. They have a one-part waist. The workers lack a stinger but have an opening at the end of the abdomen from which they spray defensive chemicals (acidiopore).

Colonies have a single queen (monogynous). Pupa (if applicable)

Type of feeder (Chewing, sucking, etc.): Chewing

Host(s): The velvety tree ant feeds on honeydew from hemipteran plant pests (especially in groves) and on wood from trees, especially , , , sycamores and cottonwoods.

Description of Damage (larvae and adults): The velvety tree ant is omnivorous, eating both plants and including , plant exudates, honeydew, wood, and carrion.

The velvety tree ant nests in wood of live trees and excavates wood used in building structures. They cause structural damage similar to carpenter and other with which they are often confused, even by pest management experts.

These ants lack a stinger but they are aggressive, have a painful bite, and spray defensive chemicals.

The velvety tree ant is found in the USA in Arizona, California, Colorado, Nevada, New Mexico, Oregon, Texas, Utah, and Washington, and Wyoming.

References: Hoey-Chamberlain, R. & Rust, M.K. (2014). Food and bait preferences of Liometopum occidentale (Hymenoptera, Formicidae) Journal of Entomological Science 49, 30 – 43.