Epoxides and ethers are common in nature. Some important and interesting natural ethers include palytoxin (isolated from marine corral), brevisamide, and brevenal (both isolated from marine plankton). Brevenal is currently under study as a treatment for Cystic Fibrosis.
An important naturally occurring epoxide is disparlure. Disparlure is a sex pheromone of gypsy moths attracting male gypsy moths. Gypsy moth wreak havoc on certain crops. One method to battle this is to combine disparlure with an insecticide. The gypsy moths are attracted to the disparlure and are concomitantly poisoned with the insecticide.