The 469 sticky-coated red spheres, 7.5-cm-diam, hung in the 81 fruiting, unsprayed apple trees in my orchard in 1974 captured 9689 apple maggot flies, Rhagoletis pomonella (Walsh). The percentage of apples infested by apple maggot larvae was only 1.1–2.7, compared with 97.2–98.2 in 3 nearby unsprayed, untrapped check orchards, and more than 80% in each of these 4 orchards in 1972.
No takes yet. Share an insight, caveat, or question.
Ronald J. Prokopy (1975) studied this question.