Two days ago I stumbled on this hornworm caterpillar that has been parisitized by a wasp. The little white things on its back are the pupal cocoons of the wasp. Essentially, a parisitic wasp found this caterpillar, jammed its ovipositor into it, laid eggs, the larva hatched and began eating the caterpillar from the inside out before pupating. Those white cocoons will hatch into more parisitic wasps. While these wasps are incredibly beneficial and without them we'd simply be overrun with insect pests, the lifecycle is a bit awful. Charles Darwin thought so too and is quoted as "I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars."