cockroach (n.)

popular name of a troublesome, voracious insect genus, 1620s, folk etymology (as if from cock (n.1) + roach; compare cockchafer) of Spanish cucaracha "chafer, beetle," from cuca "kind of caterpillar." Folk etymology also holds that the first element is from caca "excrement," perhaps because of the insect's offensive smell.

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].