The word "蠢蛋" is formed by combining the character "蠢", meaning foolish, which is itself composed of the components "春" (spring) and "虫" (insect) to historically imply foolish or restless activity, with the character "蛋", meaning egg, composed of "疋" and "虫", here used metaphorically to refer to a person. Together, they create a compound where "蠢" modifies "蛋" to denote a foolish person.