A parasite called microsporadia lies dormant in the circulatory systems of hollyqueen ladybugs. But when scientists inject microsporadia into a common European ladybug species, the insects die within two weeks. When the ladybugs were injected with deed microsporadia or a control substance, most survive. Hollyqueen ladybugs' immune systems on the other hand have learned to deal with micro sporadia, which lets the insects use them as biological weapons. Because one way ladybugs compete is by consuming the eggs and larva of rival species. When European ladybugs eat the hollyueen ladybugs' eggs and larva they also consuming the microsporadia and die. The discovery demonstrates an important role of the immunity in evolutionary selection and shows there are many ways to lose a food fight.