She was the first female professor of zoology and head of department in Ireland, and devised a technique for the identification of chironomid flies that is still employed today.

[3] Humphries worked with Winifred Frost, T. T. Macan and H. P. Moon at the Freshwater biological station at Windermere in England from 1934 to 1936, focusing on the Benthic zone fauna in the lakes of Cumbria.

Her work looked at the taxonomy of the larval and pupal stages of Chironomidae (non-biting midges or chironomids), resulting in a publication in the Journal of Animal Ecology in 1936.

Thienemann was a co-founder of the International Society of Limnology, and he was influential in Humphries undertaking the first comprehensive study of community composition and emergence periods of the Chironomidae of the Großer Plöner See.

[1] Due to her work on freshwater Chironomidae, Humphries was an authority on the taxonomy and ecology of this group in Ireland, publishing frequently in many academic journals including Proceedings of the Royal Irish Academy.

[4] In 1957, when the British Association for the Advancement of Science convened in Dublin, Humphries was a member of the organising committee and edited the zoological section of the resulting handbook.

Zalutschia humphriesiae was named in her honour, and the UCD Carmel Humphries prize is awarded every year to the best zoology postgraduate research seminar.