BUTTERFLIES AND MOTHS. 3 
and do not perceive the insect right ‘under their eyes’’ until 
it moves. This is a case of “protective colors.” Fig. 2, 
plate I, shows some geometric moths thus protected. Other 
colors are ‘‘warning colors.’’ In this case the butterfly or 
moth either posesses the form and color of a stinging insect, 
Fig. 3, or it has colors found upon insects not eaten by birds. 
Moths having such warning colors do not hide, but expose 
themselves very openly upon some object that contrasts 
strongly with their colors and thus they become very 
plainly visible. 
The Milkweed butterfly (Danais archippus Fab.) Fig. 4, 
plate I., belongs to a genus of butterflies which are not 
eaten by birds, very likely because they are poisonous or 
otherwise offensive, hence these showy insects, being thus 
well protected, are very common wherever their food plants 
occur. The Disippus Butterfly (Limenitis disippus Gtd.) 
belongs toa genus of butterflies very palatable to birds, 
yet notwithstanding this it escapes, being no doubt mis- 
taken for the unpalatable Milkweed Butterfly, which it so _ 
closely resembles. Compare Fig. 5, plate I. with Fig. 4 of 
the same plate. 
The wings themselves consist of two thin, translucent 
or transparent membranes, which are kept apart by hollow, 
horny tubes, the ribs, costz or nerves; 
the form of the wings is usually tri- 
angular, posessing therefore three 
margins, the anterior, interior, and 
exterior or posterior margin (Fig. 6). 
The space where the fore-wings join 
the body is called the basis. The 
shape of the wings depends upon the 
ribs or veins, which have received by 
scientists special names, as well as 
Beer ee ieee ne the spaces or cells they enclose. The 
C.exterior or posterior mar- CJassification of lepidoptera is mainly 
based upon the arrangement of such veins and cells. 
gin, 
