Monarchs face many dangers, one being a protozoan parasite called Ophryocystis elektroscirrha (OE) that causes monarchs to become ill or die. This experiment’s inquiry was to determine which cleaning treatment lessens the risk of OE on milkweed during caterpillar rearing. It was hypothesized that the milkweed that wasn't washed would have the most OE. Methodology: Breed OE-free butterflies. Separate each caterpillar into a container with a leaf according to its assigned cleaning treatment. Repeat this each day until the caterpillar is in it's chrysalis. After the caterpillar eclosed out of its chrysalis, test for OE. Release butterfly if it doesn't have OE. The data showed that each treatment had deaths. In conclusion, this experiment had no caterpillars that spread OE through eating infected leaves.