THE ORGANISM AND ITS ENVIRONMENT 359 



tera (Fig. 213), are insects of incomplete metamorphosis having two 

 pairs of wings and equipped with sucking mouth parts. The squash 

 bug, the electric hght bug, and Uce, may be mentioned as examples 

 of this order. Bugs are most frequently confused with the beetles, 

 order Coleoptera, but the two are easily distinguished. The anterior 

 pair of wings in the bugs fold over each other in a criss-cross pat- 

 tern when the insect is at rest, while in the beetles the modified 

 anterior wings, termed elytra, rest with their inner margins forming 

 a straight line down the middle of the dorsal surface. The insect 

 frequently miscalled the June bug, is in reality the May beetle. 



Beetles, Coleoptera, are insects of complete metamorphosis (Fig. 

 214). The number of known species is very great; it is probable 

 that there are more varieties of beetles still unknown than there are 

 known. The larva and adult may both be injurious. Common ex- 

 amples of beetles are numerous; we call attention to a few, the 

 weevils, fireflies, stag beetles, and lawn beetles. 



Butterflies and moths are frequently confused. Both are members 

 of the order Lepidoptera but are rather easily distinguishable. Moths 

 always have antenna shaped somewhat like feathers (Fig. 215), 

 while those of butterflies are smooth with a knob or spindle-shaped 

 enlargement on the end. Lepidoptera are insects of complete meta- 

 morphosis; in most cases the larvae are the damaging feeding stage. 

 Some adult Lepidoptera live only to reproduce and do not feed. 

 The coloration of the wings is often arranged in a definite pattern 

 that imitates some other object, as a leaf or a bit of bark, or mimics 

 some other organism. Protective coloration is so complete in some 

 that an observer must look closely to distinguish between the insect 

 and its background. Protective coloration is perhaps most interest- 

 ing among insects and particularly among moths and butterflies, 

 but is not confined to this group of animals. In fact, all animals 

 exhibit this structural adaptation to a greater or lesser extent. 



Members of the order Hymenoptera and of the order Diptera 



