vespillo.

Uncertain. Possibly a derivative of vespa (“wasp”). Festus describes vespa and vespula as synonyms of vespillo in this sense, but denies a connection to the 'wasp' lexeme and instead gives a (likely folk etymology) derivation of these three terms from vesper (“evening”). Thus, a semantic connection with wasps was apparently not obvious to Festus. Regardless, some modern etymologists have favored this derivation; Benveniste 1923-1924:124f argued that wasps were noted for carrying the body of their prey to their nests. The second element may be the diminutive suffix -illus, followed by -ō, -ōnis m (suffix forming appellations) making the overall structure vespa + -illus + -ō. De Vaan cites Watkins 1969 for a proposal that the word comes instead from a PIE root for 'clothing' or 'shroud' and is cognate to Hittite [script needed] (wašpaš, “clothes”).