Old English flea "flea," from Proto-Germanic *flauhaz (source also of Old Norse flo, Middle Dutch vlo, German Floh), perhaps related to Old English fleon "to flee," with a notion of "the jumping parasite," but more likely from PIE *plou- "flea" (source also of Latin pulex, Greek psylla; see Pulex).
Chaucer's plural is fleen. Flea-bag is from 1839 as low slang for "a bed;" by 1942 in British slang as "a dog." Flea-collar is from 1953. Flea-pit (1937) is an old colloquial name for a movie-house, or, as OED puts it, "an allegedly verminous place of public assembly." Flea-circus is from 1886.
"A man named 'Mueller' put on the first trained-flea circus in America at the old Stone and Austin museum in Boston nearly forty years ago. Another German named 'Auvershleg' had the first traveling flea circus in this country thirty years ago. In addition to fairs and museums, I get as high as $25 for a private exhibition." ["Professor" William Heckler, quoted in Popular Mechanics, February 1928. Printed at the top of his programs were "Every action is visible to the naked eye" and "No danger of desertion."]
genus of the flea family, Modern Latin (Linnaeus, 1735), from Latin pulex "flea," from PIE*plou- "flea" (source also of Sanskrit plusih, Greek psylla, Old Church Slavonic blucha, Lithuanian blusa, Armenian lu "flea").
"brownish-purple," literally "flea-color," 1787, from French puce "flea-color; flea," from Latin pucilem (nominative pulex) "flea," from PIE *plou- "flea" (source also of Sanskrit plusih, Greek psylla, Old Church Slavonic blucha, Lithuanian blusa, Armenian lu "flea").
[T]he couleur de Puce, or flea colour, and the couleur de Noix, or nut colour, are the reigning winter taste. [Westminster Magazine, January 1777]
Perhaps so called as the color of the scab or stain that marked a flea-bite; flea-bitten was a color word in English to describe whiter or gray spotted over with dark-reddish spots (by 1620s, often of the skins of horses, dogs, etc.). That it could be generally recognized as a color seems a testimony to our ancestors' intimacy with vermin.
OED sees no connection between this word and obsolete puke (16c.-18c.; hence Shakespeare's puke-stocking) as the name of a dark color of now-uncertain shade (Century Dictionary says perhaps reddish-brown, OED says bluish-black or inky; others suggest grey).