Bug Blog

How To Recognize The Physical Appearance And The Nesting Behaviors Of The Two Most Common Carpenter Ant Pest Species In Arizona

Camponotus is the largest genus in the ant family Formicidae with more than 600 documented species worldwide. Ants belonging to the genus Camponotus are commonly known as “carpenter ants” due to their habit of excavating nests within wood. Numerous carpenter ant species can be found throughout the US, some of which are economically significant structural pests. While all carpenter ant pest species are capable of establishing indoor nests, only some are known for nesting within the moist structural wood of homes and buildings.

Much like termites and some wood-boring beetle pests, some carpenter ant pest species occasionally excavate nesting tunnels within woodwork, resulting in costly damage. However, unlike termites, carpenter ants do not eat wood, and even the most destructive carpenter ant species often infest homes without nesting in structural lumber. Camponotus modoc and C. vicinus are the two most common and destructive carpenter ant pests in Arizona, and they are easy to recognize due to the noticeably large size of their foraging workers. These two pest species are commonly known as the “western black carpenter ant (WBCA)” and the “bicolored carpenter ant (BCA),” respectively.

The workers of most carpenter ant species are often said to be the largest ants in North America, and WBCA and BCA are no exceptions, as workers of both of these species are between ¼ and ½ inch in length. The WBCA is black and shiny with dark red legs, while the BCA is usually reddish-black. WBCA live in colonies that grow to contain around 50,000 or more workers, and mature BCA colonies contain around 100,000 workers. New carpenter ant colonies are established within natural and moist wood sources by a pair of male and female swarmers (alates), and female alates that survive go on to become queens.

Mature colonies are composed of a single parent nest where the queen and her offspring reside, as well as numerous interconnected satellite nests that workers establish while expanding their foraging range. Workers from both the WBCA and the BCA species are known for establishing one or more satellite nests within hidden indoor areas, such as wall and ceiling voids. In order to eliminate carpenter ant infestations, it is not only necessary to pinpoint and destroy all satellite nests, but also the parent nest, which can be located in logs, dead portions of trees, or fallen branches as far as 60 feet away from infested homes. Workers from BWCA and BCA colonies forage only at night, and they travel between food sources and nesting sites along fixed foraging trails. Because of this, hidden nests can be located by following workers as they forage during the early morning hours.

Have you ever found carpenter ants in your home?