Nepeta is a genus of about 250 species of flowering plants in the family Lamiaceae. The members of this group are known as catnips or catmints because of their famed effect on cats—nepeta pleasantly stimulates cats' pheromonic receptors. The genus is native to Europe, Asia and Africa, with the highest species diversity in the Mediterranean region east to mainland China. It is now common in North America as a weed. Most of the species are herbaceous perennial plants, but some are annuals. They have sturdy stems with opposite heart-shaped, green to grayish-green leaves. The flowers are white, blue, pink or lilac and occur in several clusters toward the tip of the stems. The flowers are tubular and spotted with tiny purple dots. The scent of the plant has a stimulating effect on cats.

Oil isolated from catnip by steam distillation is a repellent against insects, in particular mosquitoes, cockroaches and termites. Research suggests that in a test tube, distilled nepetalactone, the active ingredient in catnip, repels mosquitoes ten times more effectively than DEET, the active ingredient in most insect repellents, but that it is not as effective as a repellant on skin.