Dasyneura ulmea Felt ["Phytophaga ulmi" is listed causing the same symptom]
Hosts: Ulmus
Blasted buds, immature leaf clusters, or swollen seeds of slippery elm midge, spring. PI. 10 (3); Fig. 185.
”- EP Felt: (1940) Plant Galls and Gall Makers©
Reference: https://babel.hathitrust.org/cgi/pt?id=wu.89041294323&view=1up&seq=240&q1=185