I’ve got a couple Bushel & Berry patio blackberries in containers on my porch, and these guys showed up out of NOWHERE yesterday. The photo makes them look greenish, but they’re more black in person.

Does anyone know what they are? I blasted them with the hose and knocked as many off as I could, but is there a more effective way to treat them? Preferably one that won’t affect pollinators, especially since they’re about to flower.