The Courtyard Report
A zoo has a courtyard outside its insect house. Flowers there open at dusk. Wild moths visit the flowers to drink nectar. During some visits, moths carry pollen between flowers. This can help those plants make seeds.
The zoo added bright lamps for evening visitors. Before the lamps were added, staff counted 60 moth feeding visits over three evenings. Afterward, they counted 18 visits over three similar evenings. The flowers and their care had not changed. Staff wanted to investigate the lighting.
Staff tested three plans: open lamps with no covers, lamps with shields, and lamps turned off. The shields directed light down onto the walkway and kept much of it away from the flowers. Staff changed only the lighting plan. They kept the same flowers, watering, and counting spot. They counted feeding visits for 20 minutes after dusk on three mild, dry evenings for each plan. They counted visits, not separate moths. A moth could visit more than once. The graph shows each plan's total.
Tests happened while the courtyard was closed to visitors. For the courtyard to open, its walkway must stay lit. The chosen plan must also have at least 42 feeding visits in the three-evening test and cost no more than $50. Open lamps and lamps turned off each cost $0 extra. Shields cost $40. Both open lamps and shielded lamps kept the walkway lit.