Monarchs are victims of the crippling protozoan parasite Ophryocystis elektroscirrha (OE). Thousands or millions of microscopic OE spores are present on the exterior of infected adult monarchs. Monarch larvae eat the latent spores that infected adults have dispersed on eggs or milkweed plants, and the parasites subsequently reproduce inside the larvae and pupae. Because they get caught or are too weak to properly extend their wings, monarchs with severe OE infections may not successfully emerge from the pupal stage. Mild OE infections can make monarchs appear normal, but they have shorter lifespans and are less able to fly than healthy monarchs.