1. Either the axil of the scale is galled, or the galled fruit is distinctly coalescent with the scale; window-pit absent..........skuhravae sp. n.
— Galling of the fruit, the gall is in ripe situation never coalescent with the scale.......... [all other Semudobia spp.]
...
Gall ...galling of the "bract"; the ovoid gall is situated between the spindle of the catkin and the scale; window-pit absent (B. pubescens). In Japanese (Honshu, Azegate, B. ermanii) and American (South Dakota, Black Hills, B. occidentalis) material S. skuhravae is found in fruit galls. These galls have no window-pit and are coalescent with the scale. When gall and scale are separated, the membraneous cocoon of the larva becomes visible.
...
[Records from Betula alleghaniensis and B. populifolia were from cultivated trees grown outside of their natural range; not otherwise reported from these hosts.]

- J. C. Roskam: (1977) Biosystematics of insects living in female birch catkins. I. Gall midges of the genus Semudobia Kieffer (Diptera, Cecidornyiidae)^©