What kind of spider is black with an orange dot on its back?

There are a number of kinds of spiders that fit the description of being black with an orange dot on its back, so more information is needed to isolate the exact kind. Some spiders that fit that description include the Johnson Jumping spider and the Ant Mimic spider, both harmless, non-venomous spiders that sometimes bite humans but do not cause an adverse effect.

A Johnson Jumping spider generally has an irregularly shaped orange- or white-colored dot on its back. An Ant Mimic spider has a larger area of orange on its abdomen and is shaped similarly to an ant, hence the name.