She remained in that position for the remainder of her professional life. While working at the university, Patch earned a master's degree from Maine in 1910. Subsequently, she earned a Ph.D. degree from Columbia University in New York as a student of J.H. Comstock who regarded her very highly. He used part of her thesis for his Introduction to Entomology . Patch began focusing her work on the habits of aphids.
Most aphids feed on very selected species of plants and can cause serious damage to crops.
She became a recognized authority on aphids and researchers from all over the world started sending her their specimens. In 1930, she was elected president of the Entomological Society of America. One male colleague deplored the lateness of this appointment. Patch published the Food Plant Catalogue of the Aphids , an exhaustive work and a major contribution to entomology. She also published stories for children.