With Theodore D. A. Cockerell they identified 32 species in Maine and noted that some bees only visit one kind of flower such as the pickrel weed bee.
Pleurodonte guadeloupensis dominicana Pilsbry & Cockerell, 1937 - This subspecies is endemic to the Caribbean island of Dominica.
The bee expert Theodore Dru Alison Cockerell (1866–1948), who settled in the United States, was his brother, as was the book binder, Douglas Bennett Cockerell (1870–1945).
Theodore Roosevelt | Theodore Dreiser | Alison Krauss | Theodore Sturgeon | Theodore von Kármán | Alison Williamson | Theodore Roosevelt, Jr. | Alison Moyet | Aiguille du Dru | Theodore Parker | Theodore Bikel | Theodore | Christopher Cockerell | Alison Limerick | Alison Bechdel | Theodore Roosevelt National Wildlife Refuge Complex | Théodore Botrel | Charles Theodore, Elector of Bavaria | Theodore Wirth | Theodore Ushev | Theodore Robinson | Theodore of Tarsus | Theodore Edgar McCarrick | Théodore Dubois | Alison Weir | Alison Steadman | Alison Balsom | Toby Cockerell | Theodore Roethke | Theodore of Mopsuestia |
The species Formicium mirabile, named by Theodore D. A. Cockerell in 1920, and Formicium brodiei, named by John O. Westwood in 1854, are both known from fore-wings found in middle Eocene of Bournemouth, Dorset, England.