After moving to Tring, Hopkins described five new species of fleas: Xenopsylla philoxera, Hopkins 1949; Plocopsylla ulysses, Hopkins 1951; Peromyscopsylla draco, Hopkins 1951; Cratynius crypticus, Hopkins and Traub 1955; and Demeillonia miriamae, Hopkins and De Meillon 1964.
In addition, in 1958 and 1961, Hopkins donated his collection of 11,000 Phthiraptera (lice) specimens to the Natural History Museum [REF].