160 



Elementary Principles of Agriculture 



"army worms," of which the "cotton army worm" is a 

 common example in the South. Some caterpillars, 

 known as cutworms, work only at night. When daylight 



comes, they are con- 

 cealed under clods, and 

 any trash that may be 

 present. They are called 

 "cutworms" because 

 they have a habit of cut- 

 ting off young plants 

 near the ground. They 

 are the caterpillar stage 

 of several kinds of night- 

 flying moths. (Fig. 98.) 

 Thus we see that there 

 are some insects which 

 are perfectly harmless 

 in the adult stage, but 

 whose larvae do great damage. The pupal stage is inac- 

 tive, and requires no food. 



230. How Insects Get Their Food, (a) By Living 

 inside the Plant. Internal Feeders. It quite often hap- 

 pens that the egg is deposited inside of some part of the 

 plant and the larva develops there, as in the case of the 

 larva of the plum gouger. As the larva is inside of the 

 plant (Fig. 95), it cannot be destroyed by any of the 

 sprays, and, in such cases, effort is made to catch and 

 destroy the adults before the eggs are laid. 



(b) External Feeders. Insects that feed directly on 

 the leaves, fruits, etc., have mouth parts that are pro- 

 vided with scissors-like jaws by which their food is cut 

 from the plant. To destroy insects that feed in this way, 

 it is sufficient to cover the leaves with some suitable 



Fig. 98. Cutworm and moth. After 

 Howard. Bureau of Entomology, 

 United States, Department of Agri- 

 culture . 



