Only a gall remains of the type series in the USNM. Cockerell subsequently collected more adults which were described by Felt (1915b).

The gall is a spherical mass of long trichomes, about 15 mm in diameter. It consists of an aggregate of several capsules each of which encloses a larva. From the figure in Felt (1940), the gall appears to be either a node or bud gall.

In the original description (Cockerell, 1890), the host of R. alticola was given as "a composite... a Chrysopsis or Solidago." Cockerell (1909) subsequently recorded the host as "Artemisia canadensis [now considered a subspecies of Artemisia campestris]." Felt (1917) later listed "Artemisia forwoodii (? canadensis)" and, questionably, A. caudata as hosts. Baker (1895) reported a similar gall on "A. dracunculoides."

- Robert G. Jones, Raymond J. Gagné, William F. Barr: (1983) Biology and taxonomy of the Rhopalomyia Gall Midges (Diptera: Cecidomyiidae) of Artemisia tridentata Nuttall (Compositae) in Idaho^©