16 THE BUTTERFLIES OF THE 



with scales, that overlap one another and easily rub off. 

 They are divided into two somewhat natural divisions, — 

 butterflies and moths, — which may be known from each 

 other by the antennae, but by the practical entomologist 

 are readily distinguished by other characters. The an- 

 tennae, two slender organs projecting in front from the 

 upper part of the head, are filiform, and terminate in a 

 knob in butterflies, while in the moths, whatever their 

 shape, they do not terminate in a knob. Butterflies fly 

 in the daytime, while most of the moths fly at night 

 or just at the close of day. The first five families of 

 this order are known as butterflies, and all the others as 

 moths. 



Both moths and butterflies have four distinct periods 

 of existence, — the egg, the larva, the chrysalis, or pupa, 

 and the imago, or perfect insect. 



THE EGG. 



The eggs are more or less globular, cone-shaped or 

 spindle-shaped. To the unaided eye they usually appear 

 to be smooth, but under the lens they present various 

 markings that are constant for a given species, but vary 

 with different species or in different groups. Those 

 belonging to the different genera of the subfamily 

 Pierinae are all of one general shape, as has been shown 

 by Mr. W. H. Edwards. They are long, slender, sub- 

 conic or spindle-shaped, and set on end, but differently 

 marked in different genera. This may be seen by re- 

 ferring to the egg of Pieris Olwacea, Fig. 27. The 

 eggs of Danais, Heliconia, and Agraulis have each their 

 own pattern. All Argynnis eggs, whether of the large 

 or the small species, are thimble-shaped. " So Melitaea, 



