Antistrophus sp.
Skeletonplant collar gall wasp

Host: Rush skeletonplant (Lygodesmia juncea).

Gall location: On the collar of the stem, often just above or just below where the stem meets the soil. You may need to clear the soil around the base of the stem to find this gall, as its location often puts it below the soil line.

Description: Typically present as a cluster of several round, single-chambered galls, each less than a centimeter in width, around the collar. Rarely, only one or two galls are present. Green or yellowish and fleshy when fresh to brown and rough when old and dry.

Range: This gall has only been reported from Manitoba and Nebraska thus far, but its range probably matches that of the skeletonplant pea gall wasp (see next species).

This gall is induced by an undescribed species of the genus Antistrophus. This species was originally assumed to be a variant of the skeletonplant pea gall wasp, but preliminary results from an ongoing taxonomic study indicate that they are indeed different species. Galls of this species occur only on the main stem, unlike the other two species of gall wasps known from skeletonplant which occur only on the branches

- Louis Nastasi, Charles Davis: (2022) Field Guide to the Herb and Bramble Gall Wasps of North America^©