HOW TO KNOW THE BUTTERFLIES 



the latter two in the parnassians and three in the swallow-tails. 

 In the swallow-tails radius of the fore wings is five-branched, 

 veins R, and R 2 being distinct although closely parallel. 



The caterpillars are never furnished with spines, but are 

 either naked or clothed with a few fine hairs. In a single spe- 

 cies in our fauna (Laertias philenor) the body of the larva bears 

 fleshy filaments. 



A striking peculiarity of the larvse of this family is the pres- 

 ence of a pair of bright-colored fleshy " horns," which can be 

 projected from a slit in the dorsal wall of the prothorax. 

 (Plate XI, Fig. 2.) These have been termed osmateria 

 (os-ma-te'ri-a), and are supposed to be organs of defense ; 

 for they exhale, when pushed out, an odor which in some 

 species is exceedingly disagreeable. They are little long 

 pockets which are turned wrong side out when used, thus 

 throwing out in the atmosphere all of the odor that has been 

 secreted in them. These caterpillars are the polecats of the 

 insect world. 



The chrysalids are thickened in the middle and taper con- 

 siderably at each end ; they are more or less angulated, and 

 have certain parts excessively produced ; they are suspended 

 by the tail and by a loose girth around the middle. (Plate 

 XI, Fig. 1.) 



The Papilionidse includes many species ; more than twenty 

 of them have been found in America north of Mexico, and 

 eight occur in the eastern United States. The following ta- 

 ble will aid in the determination of these : 



A. With a red or orange-colored spot on the upper side of 

 the hind wings near the anal angle ; club of antenna; usually 

 strongly curved upward. 



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