ARTHROPODA 



97 



most notorious insect pests. The work of the 

 locust has been dreaded since the days of the 

 Pharaohs and before : the Colorado beetle which 

 infests the potato, is a plague as terrible, if more 

 modern. The weevils and caterpillars that de- 

 stroy trees, though not directly dangerous to our 

 food supply, are sufficiently 

 destructive. The terror of 

 insect pests lies in their vast 

 numbers, which may render 

 an otherwise harmless crea- 

 ture dangerous. I read last 

 year of a curious railway 

 mishap in the United States. 

 A train was brought to a 



standstill by the wheels slid- FIG. 3 2.-insect pests. A, 

 ing on something greasy Locust, 

 that covered the track. It 

 proved to be a flock of the 

 so-called "Army worm," a 

 variety of caterpillar which 

 travels long distances in 

 crowds, when its numbers 

 have become too many for 

 the supply of food, or when 

 it is about to enter into the pupa stage. These 

 covered the railway track, and the whole country 

 for a long distance; and the "greasiness" of the 

 rails was produced by the crushed bodies of the 

 unfortunate caterpillars. The train was delayed 

 for hours, while a gang of men with brooms 

 cleared the way in front of it. 



pere- 



grtnum, one-fourth nat- 

 ural size ; , Caterpillar 

 of Wood Leopard Moth, 

 Zevtzera Azsculi, bor- 

 inp in word, about one- 

 thirtieth of natural size ; 

 C, Colorado Beetle, one- 

 fourth ratural size ; D, 

 Leaf-rolling Weevil of 

 the Oak. 



