Phanacis taraxaci
Dandelion gall wasp
Host: Dandelion (Taraxacum officinale).
Gall location: On the leaf, often extending from the very base of the leaf all the way up the petiole and midrib.
Description: Spherical to oval-shaped, blister-like, single-chambered galls, often only a few millimeters in length. Typically quite abundant, and sometimes with multiple adjacent galls clustered together or otherwise confluent.
Range: Dandelions are found throughout North America, but thus far, this gall has only been observed in a handful of northern states and provinces, including Pennsylvania, Michigan, Minnesota, Oregon, Quebec, and Saskatchewan. These galls certainly exist elsewhere within the range of the host plant.
This species was introduced to North America from Europe along with its host plant. Interestingly, this gall was first described in North America prior to its discovery in Europe. Because dandelions are often considered weeds and are frequently culled, this gall generally appears to be more common in areas that are not actively maintained.
The dandelion gall wasp and the catsear gall wasp (Phanacis hypochoeridis), both of which are introduced species, are the only representatives of the gall wasp tribe Phanacidini to be found in North America.
