While the pupating larva is in a state of "dormancy" in its cocoon, these discs suddenly begin growing rapidly and replace the larval cells-- "just as if there were aliens hidden in a person's body which suddenly came squirming out and usurped the person's original form."
顏聖紘說，幼蟲體內有一團細胞，稱為「成蟲盤細胞」，在結網成蛹的「休眠」狀態，這一團細胞會忽然大量成長，將過去的幼蟲細胞替換掉，「就好似人身上藏著異形，突然扭曲而出，將人的原形取而代之。」