This interest was passed along to his oldest son, Henry, who became familiar with the habits of the wild creatures in the neighborhood of Detroit at an early age.

He entered Harvard University in 1869 and worked closely with Hermann August Hagen, Carl Robert Osten-Sacken, and especially Eugene Amandus Schwarz, who became Hubbard's lifelong friend.

[2] After graduation, he briefly spent time as a post-graduate working under Hagen to study the hibernation of Coleoptera (beetles) during winter.

In company with Schwarz, they made several collecting trips in and around Detroit in 1874, through Florida in 1875, and then, in 1876, a series of expeditions to the region of Lake Superior.

The collection they built was reviewed favorably by the entomologists attending the annual meeting of the American Association for the Advancement of Science, held in Detroit in 1875.

John Lawrence LeConte, the noted coleopterist, declared that the wealth of new specimens would force him to adjust parts of his beetle classification scheme.

[4] In 1880, Hubbard was appointed a special agent for the United States Entomological Commission and he began an intensive study of the insect pests affecting the Florida citrus crops.

After Florida's "Great Freeze" in 1896, Hubbard studied the ambrosia beetles that infested the dead and dying citrus trees.