Figure 1. Diagram of cages used in the three treatments.

Triangles above cages are feeders, and the circles on the sides represent the screening between cages. The 2∶1 ratio of bees in the image represents the ratio of older bees to young bees (labeled on top of each cage). Multiple bees were kept in each cage, ranging between 10 and 70 bees. In the 2-Screen Test, but not in the 1-Screen Test, there was spacing between paired cages to prevent food exchange between bees in the two cages.