Bullock’s orioles regulate the populations of black olive scale insects (Parlatoria oleae), which in large numbers have the potential to destroy olive crops.
Bullock's Orioles eat insects and other arthropods, as well as fruit and nectar. They glean insects from leaves, branches and trunks; they also pluck insects from spiderwebs or from the air, and take ripe fruit from bushes and trees. Bullock's Orioles use a method called "gaping" to extract juice from fruit, and also sometimes from tough-skinned caterpillars. Thrusting their closed bills through the skin and into the flesh of the fruit or animal, they then pry their bills open inside and lap up the pooling juices with their brushy tongues.