formication

Formication is an abnormal skin sensation similar to that of insects crawling over or within the skin. The word derives etymologically from the Latin word, formica, meaning "ant". The causes of formication can be actual physical conditions, including diabetic neuropathy, menopause, skin cancer, or herpes zoster, and may also be physical or psychological side effect of substance abuse. Formication is a specific form of the general set of abnormal skin sensations known as Paresthesia.
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Formication /for·mi·ca·tion/ a sensation as if small insects were crawling on the skin. for·mi·ca·tion n. [more]Formication - Community and Resources

Noun
1. hallucinated sensation that insects or snakes are crawling over the skin; a common side-effect of extensive use of cocaine or amphetamines
(hypernym) paresthesia, paraesthesia
(derivation) formicate

(n.)
A sensation resembling that made by the creeping of ants on the skin.
  

The sensation of bugs crawling over one's body