12. THE PARASITES OF PLANTS. 



Illustrative material: Portions of a plant that are being in- 

 jured by an insect or a fungous disease. A blighted twig from 

 an apple or pear tree, a scabby apple or potato, or a smutted 

 head of grain will illustrate the latter. 



The Potato Beetle. Nearly every American boy and 

 girl has seen the potato beetle. (Figure 24.) This is 

 an insect that feeds on 

 the leaves of the potato 

 plant. The potato 

 beetle is a parasite of 

 the potato plant. There 

 are also very small 

 plants that sometimes 

 grow within and be- 

 tween the cells of the 

 potato plant, causing 

 the leaves to die, and 

 the tubers to rot. Any 



animal Or plant that Fi* 24-- Potato beeUes. larva, and eggs. 



lives in or within a larger animal or plant, feeding 

 upon its substance, is called a parasite. The plants 

 that live upon or within animals or other plants mostly 

 belong to the class known as fungi. A single plant of 

 this, class is called a fungus, and parasites of this class 

 are called fungous parasites. Parasites are generally 

 harmful to the plants or animals on which they live. 

 Poison for the Potato Beetle. We learned in Lesson 



55 



