THE INSECTS: HEXAPODA 



105 



mens of another plant of the same species. This is the case 

 with many of the fruit trees. 



The wind carries pollen for some plants which have their 

 stamens and pistils more or less exposed, but a great number 

 of plants, especially those with the most beautiful flowers, 

 depend on insects to bring about pollination. So far has 

 this dependence gone that, in many cases, plants have be- 

 come unable to pollinate themselves. It is now clear that 

 the color, scent, nec- 

 tar, and form of flow- 

 ers, in many cases, 

 have been developed 

 in connection with 

 insect visitors. The in- 

 sects most concerned 

 in the pollination of 

 flowers are flies, butter- 

 flies, wasps, and bees. 



Some insects visit 

 flowers for the sake of 

 the nectar. Pollination 

 results from the insect 



brushing itself against the pollen-bearing organs and subse- 

 quently rubbing this pollen on to the pistil in a neighboring 

 flower in the search for nectar. But the case of the yucca moth 

 (Tegetic'ula, Fig. 65) is somewhat different. The yucca moth 

 is a white moth a little over a centimeter (about half an inch) 

 long, which lives in the flower of the yucca, or Spanish bayo- 

 net, a familiar plant of the dry southwestern plains. During 

 the day the female remains quiet, but at dusk (in the breed- 

 ing season) she begins laying her eggs within the pistil of 

 the flowers, among the ovules, which, when the flower is fer- 

 tilized, are to grow into seeds. Upon these seeds the larva 

 will feed. If this were all, there would be no peculiarity 



Fig. 65. Yucca moth. (Natural size) 

 After Riley 



