ADAPTIVE COLORATION 223 



are many exceptions to this rule. These warning colors, how- 

 ever, fail to accomplish their supposed purpose in the follow- 

 ing instances, given by Juclcl. Taking insects that are thought 

 to be protected by an offensive odor or a disagreeable taste : 

 Heteroptera in general are eaten by all insectivorous birds, the 

 squash bug by hawks and the pentatomids by many birds; 

 among Carabidse with their irritating fluids, Harpalus caligi- 

 nosus and pennsylvanicus are food for the crow, catbird, robin 

 and six others; C ambus and Calosoma are relished by crows 

 and blackbirds ; Silphidae are taken by the crow, loggerhead 

 shrike and kingbird; and Leptinotarsa decemlineata is eaten 

 by at least six kinds of birds : wood thrush, rose-breasted gros- 

 beak, quail, crow, cuckoo and catbird. Of hairy and spiny cat- 

 erpillars, Arctiidse are eaten by the robin, bluebird, catbird, 

 cuckoo and others; the larvae of the gypsy moth are food for 

 the blue- jay, robin, chickadee, Baltimore oriole and many 

 others [thirty-one birds, in Massachusetts] ; and the spiny 

 caterpillars of Vanessa antiopa are taken by cuckoos and ori- 

 oles. Of stinging Hymenoptera, bumble bees are eaten by the 

 bluebird, blue-jay and two flycatchers; the honey bee, by the 

 wood pewee, phcebe, olive-sided flycatcher and kingbird; 

 Andrena by many birds, and Vespa and Polistes by the red- 

 bellied woodpecker, kingbird, and yellow-bellied flycatcher. 



These facts by no means invalidate the general theory, but 

 they do show that " disagreeable ", qualities and their associ- 

 ated color signals are of little or no avail against some enemies. 

 The weight of evidence favors the theory of warning colora- 

 tion in a qualified form. While conspicuous colors do not 

 always exempt their owners from destruction, they frequently 

 do so, by advertising disagreeable attributes of one sort or 

 another. 



The evolution of warning coloration is explained by natural 

 selection; in fact, we have no other theory to account for it. 

 The colors themselves, however, must have been present before 

 natural selection could begin to operate; their origin is a ques- 

 tion quite distinct from that of their subsequent preservation. 



