[1] The galls, shiny and hard, turn red in colour and then black or dark purple.

The galls, formed of flattened projections, often enclose the immature acorn.

[1] The galls first appear pink in colour and as they mature they turn red, then green and finally brown during their development.

One study identified twenty-four parasitoids from galls of A. grossulariae,[6] such as Torymus auratus, Megastigmus dorsalis, Ormyrus pomaceus, Sycophila variegata, Sycophila biguttata, Mesopolobus xanthocerus, and Aulogymnus trilineatus.

[7] A. grossulariae has been recorded from the United Kingdom, Spain, Belgium,[8] and Israel.