A new study found that brood parasitism exists between two predatory mite species that have a common prey and egg predator, and sometimes prey on each other’s younger stages. Gynaeseius liturivorus is a mite species that guards its eggs, whereas Neoseiulus californicus uses this protection to safeguard its own eggs, thereby engaging in brood parasitism. However, it was observed that this brood parasitism was subject to the presence of an egg predator—western flower thrips (Frankliniella occidentalis). In the absence of this egg predator, the parasite mite did not prefer to add its eggs to those of the host mites. This suggests that brood parasitism is dependent on the threat to the parasite offspring.