30 BUTTERFLIES 



hoppers, which are green throughout with Hnear bodies, 

 and long, slender legs and antennae. 



Each of these three groups of insects is adapted to its 

 particular habitat. All are constantly persecuted by 

 birds, and have been so persecuted for unnumbered ages in 

 the past. In every generation the individuals have 

 varied, some toward closer resemblance to environment, 

 others in an opposite direction. The more conspicuous 

 insects have been constantly taken, and the least con- 

 spicuous as constantly left to reproduce. Were the three 

 groups to change places to-day, the green grasshoppers 

 from the meadows going to sandy surfaces, the sand- 

 colored locusts going to rocky hills, and the "mossbacks" 

 from the hills to the lowland meadows, each would be- 

 come conspicuous, and the birds would have such a feast 

 as is seldom spread before them. 



The species living on sand and rocks are often "flushed" 

 by birds. Those which flew but a few feet would be 

 likely to be captured by the pursuing bird; those which 

 flew farther would stand a better chance of escaping. 

 Similarly, those which flew slowly and in a straight line 

 would be more likely to be caught than those which flew 

 rapidly and took a zigzag course. As a consequence of the 

 selection thus brought about through the elimination of 

 those which flew slowly along the straight and narrow way 

 that led to death, you will find that most locusts living in 

 exposed situations when startled fly some distance in a 

 rapid, zigzag manner. 



But still another element of safety has been introduced 

 by some species of these locusts through the adoption of 

 the color tactics of the Catocala moths. The under wings 

 of the common Carolina locust — the species most abund- 



