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Vollenhovia emeryi in Washington DC

Vollenhovia emeryi nesting in dead log. Notice how these cylindrical short-limbed ants are so adept at weaving among their shallow nest tunnels. This colony had hundreds of workers and many queens. Units in mm. Collection data: USA Washington DC, C&O Canal, 16.vi.2011, 38.902739°, 77.057704°, 3m, E.M. Sarnat.

Vollenhovia emeryi is one of the more recent ants to have established in North America. The first record of this Japanese transplant came from Stefan Cover of Harvard’s Museum of Comparative Zoology. Cover discovered the species in 1986 while sampling for ants in Washington, DC. Vollenhovia species tend to be generalists and the native range of the genus is restricted to Asia, northeastern Australia, and the Pacific Islands, and are not generally thought of as successful tramp ants.

How then did this demure little species come to arrive in the capital city of the United States? The answer might be linked to a tale often told of that city’s namesake, George Washington. Legend has it that when George Washington was a six-year-old lad he chopped down a cherry tree. When confronted by his father, young George replied, “I cannot tell a lie, father, you know I cannot tell a lie! I did cut it with my little hatchet.”

Cherry trees may, in fact, have been how Vollenhovia emeryi became introduced into the United States. Japan has gifted the cities of Washington DC and Philadelphia thousands of cherry trees during the past century, many of which were planted in localities where V. emeryi is known to occur. Dan Kjar raises the possibility that colonies of these little ants stowed away in the rootballs of the cherry trees, and have slowly been expanding their range along the riparian habitats of the District of Colombia, Virginia, Maryland, and Pennsylvania ever since.

During my recent research trip to the Smithsonian’s entomology collection I took a brief expedition in search of a Vollenhovia emeryi colony to collect and film. Dan Kjar suggested I take a look around the C & O Canal area near Georgetown. By the time I exited the Metro station it was pouring down rain, so I concentrated my search to a relatively dry area under a freeway overpass. Searching for invasive ants often leads one to rather unsavory habitats, such as dumps, ports, and urban filth. After turning over all variety of garbage and refuse in search of a colony, I finally found one nesting under a dry branch.

Eli Sarnat collecting live colony of Vollenhovia emeryi from beneath an overpass in Washington DC. Notice the graffiti and garbage strewn across the site. Invasive ant research is not always the stuff of romance.

I took some video of the ants as they scurried about in their signature slinky style. Then I searched about the garbage some more until I found a suitable empty Gatorade bottle and a mismatched cap into which I collected the live colony. The colony had many queens, so I split it in two. One colony is now residing happily in Ted Schultz’s ant lab at the Smithsonian, and the other is at the Suarez Lab at UIUC. Alex Wild took some excellent photographs of these ants from the Suarez lab colony that are available on his Myrmecos website.