214 



AGRICULTURE 



Beetles. Beetles have four wings. The fore wings, called 

 sheath wings, are hard and often bright-colored; the thin hind 

 ones are kept folded under the sheath wings. Beetles are often 

 injurious in the imago as well as in the larva form. 



Colorado Potato Beetle. This is the case with the Colorado 

 potato beetle. It was an invasion of this insect that brought about 



the use of Paris green as an in- 

 secticide, which has saved mil- 

 lions of dollars' worth of crops. 

 The potato beetle is a native of 

 the Rocky Mountains. There, it 

 feeds on weeds of the nightshade 

 family, to which the potato be- 

 longs. Within thirty years, it 

 has extended its home to most 

 parts of the United States. 



The black-and-yellow beetle 

 winters in the ground. It comes 

 out in the spring and feeds rav- 

 enously on the potato, horse 

 nettle, and eggplant. The female 

 deposits its little yellow eggs 

 six hundred to a thousand in number in patches on the under 

 side of the leaves. These eggs hatch in a few days into slug-like 

 larvae. The beetles are hungry, but the larvae are ravenous. 

 They feed greedily for four or five weeks, then enter the ground 

 and come forth in a few days as beetles. There are three or 

 four broods every season. 



To stop the ravages of beetles, hand picking is used to some ex- 

 tent, but poison is the best remedy. The farmer is aided in the 

 work by some birds, especially crows, by ladybird beetles, and by 



COLORADO POTATO BEETLE 



Beetle, larva, and eggs are shown on this 

 spray of a potato plant. 



