66 BUTTERFLIES 



found from the Carolinas to California, being at times ex- 

 tremely abundant in certain localities over this great 

 region. It seldom occurs as far north as New England 

 and in a general way east of the Hocky Mountains its 

 northern limit approximates that of forty -three degrees of 

 latitude. It varies considerably in size and differs greatly 

 in abundance in different localities and different seasons. 

 Probably the commonest food plant of the caterpillars 

 is the Dutchman's Pipe or Aristolochia, which is fre- 



Caterpillar of the Blue Swallowtail, (After Riley) 



quently planted as an ornamental vine for porch aaorn- 

 ment. It also feeds upon wild ginger or Asarum and 

 probably upon other plants. A dozen or more eggs are 

 laid upon a leaf by the mother butterfly, usually in a clus- 

 ter or grouped near together. They hatch a week or so 

 later into small brownish caterpillars which remain to- 

 gether for awhile in little groups that feed side by side 

 upon the leaf, beginning at the margin and working toward 

 the centre. As they become larger they feed more freely 

 and gradually disperse so that each forages for himself. 

 As they approach maturity their appetites become vora- 

 cious and their presence is often shown by the defoliated 

 condition of the branches. They have back of the head 

 the osmateria or scent organs which are commonly found 



