THE INSECT WORLD. 



241 



inches. Many of the Lepidoptera are useful in poUenizing 

 flowers, some, indeed, depending entirely upon them for their 

 continued existence, but, on the other hand, the caterpillars, as 

 the larvae are usually called, are among the most troublesome 

 and injurious insects with which the agriculturist has to deal. 

 The transformation in this order is complete, and a greater 

 difference than that between caterpillar and butterfly can hardly 

 be imagined ; while in the chrysalis or pupa we have a quiescent 

 period where scarcely even the form of the future insect is indi- 

 cated, and when it is absolutely incapable of motion. 



Broadly, the order is divided into butterflies and moths, or, 

 more accurately, the Rhopalocera and Heterocera. Rhopalocera 

 are those in which the antennae, or 

 feelers, terminate in a more or less 

 distinct knob or club at the tip, and 

 in which at least the front pair of 

 wings are elevated or vertical when 

 at rest, so that the upper surfaces 

 touch. The Heterocera, on the 

 other hand, have feelers, or anten- 

 Uce, of many different kinds, but 



distinctly 

 when the 

 horizontal. 



Fig. 250. 



fauna 



never m our 

 clubbed. The wings 

 insect is at rest are 

 folded on the back or close to the 

 sides, oblique, roof-like, or spread 

 out flat, but never habitually ver- 

 tical. In general it may be said 

 that the butterflies are on the 

 wing during the day, and fly dur- 

 ing the night only in rare in- 

 stances ; moths, on the other hand, 

 are night flyers, as a rule, though there are many exceptions, 

 and a number of species occur commonly during the day. 



The butterflies separate readily into groups based on the char- 

 acter of the feet and the situation of the antennae. What may 

 be called for convenience the " true butterflies " are distinguished 

 by having the feelers set close together on the top of the head, 

 the latter being proportionately rather narrow. The antennal 



16 



Antennas in Lepidoptera. — a, 

 clubbed antenna of butterfly ; b, c, 

 variations in form of club; d, prismatic 

 and fusiform ; e, ciliated ; f, bristle- 

 tufted ; g, doubly bipectinated. 



