The tiny black Argentine ants are a real problem. In Southern California many consider them a threat on the same level as Varroa. Try to find the colony(ies) and control them otherwise they will establish themselves under the hive or pallet and ruin the bees. Gets worse starting in July. I dug out a bunch of old bee pallets with the U clips to use this Spring, down in a river bottom, and sure enough within 3 weeks the little so and sos had moved in to the crack between two hives. You won't have that with W clips.