THE SVvALLOWTAILS 59 



with them can recognize the chrysalis and know the kind 

 of butterfly it will produce. 



The Black Swallowtail 



Papilio polyxenes 



While the Black Swallowtail is not so large as some other 

 members of the group, it is probably the best known to 

 most people. It is found throughout many months of the 

 year in practically all parts of North America south of 

 Canada, and has the habit of flying freely about fields and 

 gardens in search of flowers from which to suck its nectar 

 food, and of plants on which to deposit its eggs. The fe- 

 male butterflies have a remarkable ability in selecting only 

 members of the great family Umbelliferae for this purpose. 

 In consequence the caterpillars are generally to be found 

 feeding upon carrots, parsnips, parsley, and various wild spe- 

 cies belonging to this order. (See plates, pages 48 and 6^-65.) 



The eggs of the Black Swallowtail are laid one in a 

 place upon the leaves of the food plant. Each egg is a 

 small, yellowish, smooth, and ovoid object. It may 

 often be found by watching the butterflies as they fly low 

 in search of umbeUiferous plants, and seeing one stop for a 

 minute or so while she lays the egg. 



About ten days after the egg is laid it hatches into a 

 small black caterpillar marked in a characteristicjfashion 

 with a blotch of white in the muddle of the body which is 

 suggestive of a saddle. The caterpillar immediately be- 

 gins to feed upon the green substance of the leaf, continu- 

 ing thus about a week before the first moult. At this 

 time it does not change much in appearance, still being a 



