What should I do if I suspect a monarch I'm raising has OE or some other disease?

It is best to keep monarchs in individual containers, since disease can spread quickly when multiple individuals are housed together. Ophryocystis elektroscirrha (OE) can spread if adults share space with eggs or caterpillars, and caterpillars kept in the same enclosure are more likely to transmit viral or bacterial pathogens, many of which are fatal. If you notice an individual that appears sick, handle it last and take care to avoid contaminating other containers.

Diseases and natural enemies are a natural part of monarch ecology, so if an individual dies, it can be returned to the outdoors. If an individual is still alive but clearly showing symptoms that would prevent it from surviving in the wild, you may choose to euthanize it—freezing is one common and humane method.

For more information please see our Rearing Monarchs For Research: A Guide for Enthusiasts handout.