Dilworth Darwin Jensen (1910-1973) earned his Ph.D. degree from the University of California, Berkeley in 1943 under the direction of Professor E.O. Essig. Following a short time with the USDA working with stone fruit and papaya viruses, Dr. Jensen joined the University of California, Berkeley, faculty in 1946. His life’s work focused primarily on the transmission of viral plant pathogens by homopterous insects, Psyllidae and others. He maintained a life-long interest in the systematics of the Psyllidae but was never able to devote the attention to it that he wished.
The Jensen Psyllid Collection comprises approximately 22,000 specimens. Specimens from western North America make up the majority of the material. However, an identified, European collection is maintained as well. Approximately two-thirds of the specimens are preserved in alcohol. The collection also includes approximately 800 slides and some 6000 pinned specimens. All specimens bear lot numbers which reference field notes and additional data in a card file. Alcohol and slide material is maintained separately, while Jensen integrated his dried material with that of the rest of the collection. The collection contains numerous paratypes, while Jensen’s holotypes have been placed on loan of indefinite duration at the California Academy of Sciences.
Dr. Jensen also amassed a large collection of reprints dealing with the systematics and biology of psyllids which is now part of the Essig Museum reprint collection.
Some publications based on this collection
Jensen, D.D., 1943. Chermidae: The Psyllidae of California. Ph.D. Dissertation, University of California.
Jensen, D.D., 1951. The North American Species of Psylla from Willow, with Descriptions of New Species and Notes on Biology. Hilgardia 20(16): 299-324.
Jensen, D.D., 1956. New Species of Psylla from Western United States and Biological Notes. The Canadian Entomologist 88(3): 101-109.
Jensen, D.D., 1957. Four New Species of Arytaina from California (Homoptera: Psyllidae). Journal of the Kansas Entomological Society 30(3): 89-98.