Andricus chrysobalani, new species
Consists of a larval cell horizontally placed inside of and in very base of young acorns in midsummer. Affected acorns are those of the current season whose growth has been so retarded that they are undersized (10-18 mm.), often lopsided, with the cup more or less distorted. The cotyledons do not develop inside. The exit hole is in the top of the acorn and the cup is not involved.
”- LH Weld: (1926) Field notes on gall-inhabiting cynipid wasps with descriptions of new species©
Reference: https://www.biodiversitylibrary.org/page/7610802#page/339/mode/1up