102 INSECTS. 



The Species. Select two of the large swallow-tail but- 

 terflies (the large black ones with tailed hind wings) that 

 differ plainly in coloration, markings, outline, etc. These 

 are two different species. Find out all you can about the 

 two species, first by studying them, and afterward by read- 

 ing about them (you will find them described in French's 

 44 Butterflies of the Eastern United States"), and note 

 the kind of differences between them : 



1. Differences of color and markings throughout all 

 stages, very obvious differences, but not alone sufficient 

 for distinguishing species, for color is a very variable and 

 somewhat unreliable characteristic. 



2. Slight differences in outline, in external ornamenta- 

 tion, etc. 



3. Differences in size. 



4. Differences in habits. 



5. Differences in food of larvse. 



6. Differences in egg, larval, and pupal periods, etc. 

 Such minor differences as these are the ones commonly 



used for distinguishing species. Make a list of the points 

 that distinguish the two species selected. 



Get the two common kinds of cabbage butterflies. The 

 most prominent mark, within the border of the fore wings, 

 is in one a black spot, and in the other a black dash. 

 Compare these, and observe that the differences are of the 

 same kind as before. These are two species. 



The Genus. Now compare a swallow-tail with a cab- 

 bage butterfly. Note that while the two are alike in the 

 possession of relatively broad wings and slender bodies, 

 and in having six fully developed feet, their differences 

 are yet greater than those which distinguish species. 

 Note the differences : 



1. In the shape of the hind wings. 



2. In their position in relation to the abdomen. 



