Researchers wanted to determine if pesticide X was effective…

Researchers wanted to determine if pesticide X was effective at killing grasshoppers that typically invade cornfields. Two ten-acre cornfields located 1 mile apart were chosen. The cornfield to the west was sprayed only with water. The cornfield on the east received the same amount of water with a 10% solution of pesticide X. Grasshopper abundance was measured in the fields every week for 10 weeks.  The results were: West field – the number of grasshoppers doubled East field – the number of grasshoppers declined by 50% Which field was the control group?