cockroach (n.) Look up cockroach at Dictionary.com
1620s, folk etymology (as if from cock + roach) of Spanish cucaracha "chafer, beetle," from cuca "kind of caterpillar." Folk etymology also holds that the first element is from caca "excrement."
A certaine India Bug, called by the Spaniards a Cacarootch, the which creeping into Chests they eat and defile with their ill-sented dung [Capt. John Smith, "Virginia," 1624].