COLOR AND PATTERN IN ANIMALS 417 



doubtedly the result of previously made trials; that is, it has 

 been learned by experience. Now it would obviously be of 

 advantage to those species of insects that are ill-tasting, if 

 their coloring and pattern were so distinctive and conspicuous 

 as to make them readily known by birds, and once learned 

 easily seen. A distasteful caterpillar needs to advertise its 

 unpalatability so effectively that the swooping bird will recog- 

 nize it before making that single sharp-cutting stroke or peck 

 that would be as fatal to a caterpillar as being wholly eaten. 

 Hence the need and the utility of warning colors. And indeed 

 the distasteful insects, as far as recognized, are mostly of con- 

 spicuous colors and patterns. 



Such warning colors are presumably possessed not only by 

 unpalatable insects, but also by many that have certain special 

 means of defense. The wasps and bees, provided with stings, 

 dangerous to most of their enemies, are almost all conspicu- 

 ously marked with yellow and black. Many bugs, well defended 

 by sharp beaks, possess a conspicuous color pattern. 



Numerous other animals besides insects also are believed 

 to have warning colors. The Gila monster (Heloderma), the 

 only poisonous lizard, differs from most other lizards in being 

 strikingly patterned with black and brown. Some of the ven- 

 omous snakes are conspicuously colored, as the coral snakes 

 (Elaps) or coralillos of the tropics. The naturalist Belt, whose 

 observations in Nicaragua have added much to our knowledge 

 of tropical animals, describes as follows an interesting example 

 of warning colors in a species of frog: 



" In the woods around Santo Domingo (Nicaragua) there are many 

 frogs. Some are green or brown and imitate green or dead leaves, 

 and live among foliage. Others are dull earth-cojored, and hide in 

 holes or under logs. All these come out only at n|ght to feed, and they 

 are all preyed upon by snakes and birds. In conHfc||^sdth these ob- 

 scurely colored species, another little frog hops about^mthe daytime, 

 dressed in a bright livery of red and blue. He can not^B mistaken for 

 any other, and his flaming breast and blue stockings^lBw that he does 

 not court concealment. He is very abundant in tlaf damp woods, and 

 I was convinced he was uneatable so soon as I made his acquaintance 

 and saw the happy sense of security with which' he hopped about. I 

 took a few specimens home with me, and tried/ny fowls and ducks 

 with them, but none would touch them. At last, by throwing down 



