An association between members of two different species in which one, the inquiline, lives on or in the other (the host), or inside the host’s home, obtaining shelter and in some instances taking some of the host’s food. For example, certain mosquitoes live and breed in the fluid contained in the pitchers of pitcher plants, benefiting from the protection afforded by the pitcher and also making use of nutrients from prey trapped by the plant. The nest of many social insects harbour inquilines, which have evolved ingenious strategies to gain food or avoid being attacked, as evidenced by the staphylinid beetle Atemeles pubicollis. As a larva this lives in ant colonies, adopting the ‘begging’ posture of ant larvae in order to receive food from adult ants.