Formicophilia, a form of zoophilia

Zoophilia

Zoophilia, from the Greek ζῷον and φιλία is the practice of sex between humans and non-human animals , or a preference or fixation on such practice...

, is the sexual interest in being crawled upon or nibbled by small insects, such as ants. This paraphilia

Paraphilia

Paraphilia is a biomedical term used to describe sexual arousal to objects, situations, or individuals that are not part of normative stimulation and that may cause distress or serious problems for the paraphiliac or persons associated with him or her...

often involves the application of insects to the genitals, but other areas of the body may also be the focus. The desired effect may be a tickling or stinging sensation, or the infliction of psychological distress on another person.