1a irregular blotch with semi-deliquescent greenish frass, containing several larvae: Delina veratri

1b corridor, with black frass in strings or grains, containing a single larva => 2

1c galls, etc => Tables for all parasites per species

2a frass in discrete grains: Liriomyza wachtlii

2b frass in strings (occurrence on this plant needs confirmation): Liriomyza bryoniae