3-Methylindole, or skatole, belongs to the indole family and has a methyl substituent in position 3 of the indole ring. It occurs naturally in feces, beets, and coal tar, and has a strong fecal odor. Its name is derived from skato, the Greek word for dung. It exists as a white crystalline or fine powder solid, and it browns upon aging. 3-Methylindole is produced from tryptophan in the mammalian digestive tract where tryptophan is converted to indoleacetic acid, which decarboxylates to give the methylindole. These reactions are largely driven by the microbiota in the digestive tract. 3-Methylindole is soluble in alcohol and benzene and it gives violet color in potassium ferrocyanide (K4Fe(CN)6.3H2O) mixed with sulfuric acid (H2SO4). Skatole has a double ring system which displays aromaticity that comes from the lone pair electrons on the nitrogen. It is continuous (all atoms in the ring are sp2 hybridized), planar, and follows the 4n+2 rule because it has 10 pi electrons. In a 1994 report released by five top cigarette companies, skatole was listed as one of the 599 additives to cigarettes. This is because in low concentrations skatole has a flowery smell and is found in several flowers and essential oils, including those of orange blossoms, jasmine, and Ziziphus mauritiana. As a result, skatole/3-methylindole is used as a fragrance and fixative in many perfumes and as a general aroma compound for other applications. 3-Methylindole has been found to be a bacterial metabolite of members of the Clostridium (PMID: 18223109) and Lactobacillus (PMID: 16345702) families. Skatole functions as an insect attractant and is one of many compounds that are attractive to males of various species of orchid bees, which apparently gather the chemical to synthesize pheromones; it is commonly used as bait for these bees for study (PMID: 12647866). It is also known for being an attractant for the Tasmanian grass grub beetle (Aphodius tasmaniae). Skatole has also been shown to be an attractant to gravid mosquitoes in both field and laboratory conditions (PMID: 24242053).