Born in East Hartford, Connecticut, the son of Archie and Adella (Ensign) Evans, he developed an interest in natural history, and insects in particular, as a child on his parents' tobacco farm.

Giardia species (G. intestinalis, G. lamblia, or G. duodenalis) is found on surfaces or in soil, food, or water that has been contaminated with feces from infected humans or animals.

His passions included field biology, writing, teaching, the American West, backpacking, fishing, classical music, environmental conservation, and his family.

Several of his books, including Life on a Little Known Planet, are among the most popular works on entomology for a general audience, and were translated into many languages and reprinted several times.

Some of his most noteworthy essays for popular audiences were published posthumously as The Man Who Loved Wasps: A Howard Ensign Evans Reader.

Also published posthumously was The Sand Wasps: Natural History and Behavior, completed by Kevin M. O'Neill from notes left by Evans.

Evans maintained an interest in poetry and wrote The Song I Sing (1951) which included a collection of poems that had he had published in Hartford newspapers.