Diastrophus cuscutaeformis
Blackberry seed gall wasp

Host: Various brambles (see remarks below).

Gall location: On the main stem.

Description: Distinctive, but often quite diverse in appearance. Typically present as large, long clusters of closely-placed, seed-like, single-chambered galls. Green when fresh to red or brown when mature. The size and shape of the individual galls is quite variable, although they usually each have fine hairy filaments, distinct spines, or blunt projections. Individual galls are less than a half centimeter in diameter. Clusters may contain only a few galls, or as many as 100!

Range: Widespread in Eastern North America, from New England and Lower Canada south to Georgia and west to Minnesota and Louisiana. This gall is one of the more common bramble galls, and it is common in many habitat types.

There is currently little consnsus on the true host plant range for this species, as the literature has been inconsistent in its mentioning and treatment of host identifications, but overall, this gall appears to be found on brambles of the subgenus Rubus, specifically species that stand erect. The authors of this guide have thus far found blackberry seed galls on Allegheny blackberry (Rubus allegheniensis) and common blackberry (R. canadensis). Host plants used by this gall can be difficult to identify, but luckily, this gall is rather distinctive.

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