Anguina pacificae feeds on the stem of Poa annua [annual bluegrass], causing stem galls ... [In North America it is] found ... only in golf courses in a narrow band along California’s northern Pacific coast. ... The second-stage juvenile ... crawls up the stem ... in a film of water[,] ... enters the leaf sheath, and crawls downward within the sheath to the stem base or crown. Generally multiple nematodes enter a single crown. They [cause] a gall ... to form around them as they feed ... [After maturing within the gall and mating there, a female] begins laying eggs, usually 1000 or more, within the gall ... Around 80 days after infection the gall begins to rot and the [juveniles] leave the gall to search for a new host. As the gall rots, the aboveground portion of the plant dies, causing chlorotic and later necrotic patches on the turf surface.

[click below for photos]

- Kammerer, Christian and William T. Crow: (2022) Featured Creatures: Pacific shoot-gall nematode^©

Reference: https://entnemdept.ufl.edu/Creatures/NEMATODE/Anguina_pacificae_Pacific_shoot_gall_nematode.htm#:~:text=Anguina%20pacificae%20feeds%20on%20the,northern%20coastal%20California%20and%20Ireland.