What insect keeps cows from nectar they give?

The insect that keeps cows from nectar is the "nectar robbing" bee, specifically certain species of bees that take nectar from flowers without pollinating them. While these bees are not directly associated with cows, they can affect the availability of nectar in the ecosystem. This can indirectly impact the overall health of plants that cows might rely on for grazing. Additionally, if cows are in areas where such bees are prevalent, it could affect their access to flowering plants, although cows primarily graze on grasses rather than nectar.