Items needed:
30 pieces of "food" (2x2 pieces, 10 red, 10 yellow, and 10 orange)
1 paper bag per girl
Before the game starts, sprinkle all the colored squares in a field, hiding them a bit to make sure they are not all easily found.

Tell the girls that they are being part of a food chain.

Divide the girls into 3 groups: grasshoppers, rats and hawks. There are 3 grasshoppers for every rat and 3 rats for every hawk. (example: a group of 26 girls would have 2 hawks, 6 rats and 18 grasshoppers.) Label the different groups with different colored arm bands.

Hand each 'grasshopper' a paper bag which will represent their stomach.

Give the girls their instructions: The grasshoppers hunt for food first. Hawks and Rats are to watch quietly on the side like good predators! Grasshoppers have 30 seconds to collect food in their "stomachs". Then the rats get to hunt grasshoppers for 30 seconds, while the grasshoppers continue to hunt for food, while the hawks watch. When a rat touches a grasshopper, it is caught and "eaten" by giving it's "stomach" to the rat. (Then the eaten grasshopper sits on the side and watches the rest.) Then the hawks get to hunt the rats for 30 seconds while the rats continue to hunt for grasshoppers and the grasshoppers continue to hunt for food. At the end of that 30 seconds all the grasshoppers, rats and hawks bring their "stomachs" to the side and sit down.

Tell the girls that there is "pesticide" in the environment. The pesticide was sprayed in order to prevent crop damage by the grasshoppers. This pesticide is one that accumulates in food chains and stays in the environment for a long time. Tell the girls that the red pieces of paper is food that was sprayed with pesticide. All grasshoppers not eaten by the rats are now dead anyway if they ate any food with pesticide. Any rat with more than half of its food sprayed with pesticide is dead also. The hawk with the most food sprayed with pesticide doesn't die but since it has accumulated so much pesticide in its body the next eggs produced will be so thin that the eggs will not be able to hatch. No other hawks are affected THIS TIME.