EXPERIMENT   A female digger wasp excavates and cares for four or five separate underground nests, flying to each nest with food for the single larva in the nest. To test his hypothesis that the wasp uses visual landmarks to locate the nests, Niko Tinbergen marked one nest with a ring of pinecones. After the mother visited the nest and flew away, Tinbergen moved the pinecones a few feet to one side of the nest.

 RESULTS   When the wasp returned, she flew to the center of the pinecone circle instead of to the nearby nest. Repeating the experiment with many wasps, Tinbergen obtained the same results.

 CONCLUSION   The experiment supported the hypothesis that digger wasps use landmarks to keep track of their nests.

Tinbergen received the 1973 Nobel prize in Medicine with Karl Von Frisch and Konrad Lorenz.