Figure 17.15 Controlling consumption of yucca seeds by yucca moth caterpillars. When female yucca moths lay 0 to 6 eggs in a yucca flower, the average plant develops 62 percent of its flowers to maturity. If a moth lays 9 to 12 eggs, the average plant only develops 17 percent of its flowers to maturity; the rest are selectively aborted. This response favors yucca moths that lay fewer eggs.
Data from O. Pellmyr and C. J. Huth, Evolutionary stability of mutualism between yuccas and yucca moths, Nature 372 (1994): 257–260.