THE AETHROPODS 403 



live on the ground are more or less protectively colored. 

 This may help them some in escaping such enemies as hawks, 

 but obviously would be of no protection against weasels, 

 skunks, and other enemies which hunt by night, guided by 

 odors and not by colors. 



Finally, it should be noted that some colors of animals are 

 probably not useful. For examples, we may mention the 

 beautiful colors concealed in shells of molluscs (Chapter XV), 

 the " eye-spots " in wings of some moths and butterflies, 

 and the gorgeous color-patterns of many birds (e.g., pea- 

 cock). For all of these and very many more we have as yet 

 no satisfactory explanations. 



335. Instincts of Insects. The instincts of insects have 

 long aroused the wonder of students of animal life, for 

 under the guidance of inherited instincts many insects 

 exhibit remarkable behavior. It is instinct which leads 

 honey-bees to build honeycomb, care for the young in true 

 nurse fashion, give a different kind of food to the larvae 

 destined to become " queens," follow the " queen " when she 

 leaves the hive at swarming time, sting intruders, and in 

 various other ways behave almost like intelligent beings. 

 It is instinct which leads parasitic species to lay their eggs 

 in the right kind of larvae, and other species to place the 

 eggs on plants which will furnish the right kind of food for 

 the young larvae. It is instinct which leads certain wasps to 

 capture and paralyze other insects, and then place them where 

 wasp larvae hatching from eggs can later eat them. In short, 

 thousands of cases of striking behavior of insects are ap- 

 parently due to instinct. Some of the actions of insects 

 suggest that they are intelligent and capable of reasoning ; 

 but the most critical studies have led entomologists to the 

 conclusion that insects do not reason, but that they con- 

 stantly act instinctively and automatically. How they 

 originally acquired their instincts is entirely unknown, 

 but that the instincts are transmitted from generation to 



