Now in summer, when it was hot, and he was very tired and ill from his journeyings, or when he held the office of lecturer, he would sometimes, as he lay thus in bonds, and oppressed with toil, and tormented also by
noxious insects, cry aloud and give way to fretfulness, and twist round and round in agony, as a worm does when run through with a pointed needle.
While still caterpillars, these
insects incorporate
noxious chemicals from the plants they eat, making them unpalatable to birds even after they metamorphose into butterflies.