234 Plant Life and Evolution 



Yucca, and the parent moth lays her eggs in the 

 ovary of the open flower, and then collects a mass 

 of pollen and forces it down the central part of the 

 stigma, thus ensuring fertilization of the ovules, and 

 the provision of a future food supply for the larvae. 

 The latter do not devour all of the seeds, some of 

 which are left, which pay for the seeds devoured 

 by the larvae. 



Birds as Agents in Cross-Pollination. While 

 insects are the main agents in cross-pollination, 

 other animals may be more or less important. Oc- 

 casionally snails have been found to act as agents 

 in pollination, but next to insects, certain families 

 of birds are of the first importance: In the warmer 

 parts of the Old World, the honey-suckers or sun- 

 birds of the large family Cinnyridse, are flower 

 visitors and are especially adapted to extracting the 

 honey from flowers, and undoubtedly like insects 

 they carry pollen from one flower to another. More 

 important still are the humming-birds of the New 

 World. They are distributed practically over the 

 whole American Continent, from Alaska to Pata- 

 gonia. They are preeminently flower visitors, and 

 very many of our native flowers are clearly adapted 

 to their visits. These " ornithophilous " flowers are 

 usually very vividly colored, bright red seeming to 

 be the commonest color. A host of tubular scarlet 

 flowers like the canna, scarlet sage, nasturtium, 

 fuchsia, scarlet columbine, trumpet creeper, etc., 

 are prime favorites of these little feathered gems. 



