wasps shared a common ancestor that evolved into distinct species based on the species of willow they preferred. Walsh also investigated the phenomena of protective mimicry among insects and argued that it was best explained as an example of natural selection. Darwin was delighted to learn of Walsh's studies and incorporated his findings in later editions of the Origin of Species. Death Walsh died on November 18, 1869 from injuries sustained when struck by a train while walking along the tracks. He is buried in the Chippiannock Cemetery, Rock Island. His insect collection, numbering 30,000 specimens, was purchased by the state of Illinois and stored in the "fireproof" facilities of the Chicago Academy of Sciences for safekeeping. Nevertheless, almost all of Walsh's collection was destroyed in the Great Chicago Fire of 1871. Publications Walsh authored 385 works during his career and co-authored an additional 478 works with Charles V. Riley. Some of his more notable entomological works include: 1861. Insects injurious to vegetation in Illinois 1864. On dimorphism in the hymenopterous genus Cynips 1864. On certain entomological speculations of the New England school of naturalists 1865. On phytophagic varieties and phytophagic species, with remarks on the unity of coloration in insects 1866. Imported insects; the gooseberry saw-fly 1867. On the insects, coleopterous, hymenopterous, and dipterous, inhabiting the galls of certain species of willow 1867. First annual report on the noxious insects of the state of Illinois 1867. The apple-worm and the apple-maggot 1868. The periodical cicada (with Riley) 1869. Imitative butterflies (with Riley) Notes References External links Benjamin Dann Walsh Field Notebooks from the Smithsonian Institution Archives 1808 births 1869 deaths American entomologists 19th-century American scientists People from Hackney, London Scientists from London Alumni of Trinity College, Cambridge English religious sceptics 19th-century English male writers English emigrants to the United States People from Henry County, Illinois People from Rock Island, Illinois People educated at St Paul's School, London Radical Republicans Illinois Republicans American abolitionists Railway accident deaths in the United States Accidental deaths in Illinois Burials in Illinois