[4][5] She married Edward W. Baker, also an acarologist, with whom she worked at the United States Department of Agriculture's (USDA) Systematic Entomology Laboratory in Beltsville, building the collection there, and in 1999 expanding the premises to accommodate more researchers.

[6] While at the USDA, Delfinado specialised in the study of bees at the Beneficial Insects Laboratory.

[7][8][9] This included the identification of the honey bee mite Acarapsis woodi and she was the first to report the presence of Melittiphis alvearius in the United States.

[10] Heavily involved with the International Journal of Acarology, she was a Chief Editor for over twenty years until her retirement in 1999.

[11] She and her husband retired to the Philippines,[12] and she established a research fellowship on mite taxonomy in his honour.