After reading the paragraphs below, answer the questions that follow. The graph below is of an index of diversity of arthropods in three different plots of a cornfield. In one of the three plots an insecticide was sprayed. Answer the questions below about this situation.

Arthropod diversity in three cornfield plots.
When and where does it appear that the insecticide was applied?
◦ in August in Plot 3
◦ in May in Plot 1
◦ in June in Plot 1
◦ in July in Plot 3