Alongside the iconic monarch butterfly, milkweed plants host other invertebrate species that impact monarch survival. For example, aphids have indirect impacts on monarch larvae when on the same host plant. Research has not explored aphid host preferences, which could augment their effect on monarchs. To address this, I tested aphid choice and population establishment on three common milkweed species. These findings can be applied to monarch conservation efforts to decrease negative impacts from aphid presence.