158 > Elementary Principles of Agriculture 



ting off young plants near the ground. They are the 

 caterpillar stage of several kinds of night-flying moths. 



(Fig. 98.) 



230. How Insects Get 

 Their Food, (a) By 

 Living inside the Plant. 

 It quite often happens 

 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 plumgouger. As the 

 larva is inside of the 

 plant (Fig. 95), it can- 

 not 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) By Feeding on the Leaves. Insects that feed 

 directly on the leaves 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 

 arsenic compound by sprays. When they eat the leaves, 

 they consume enough of the poison to induce their 

 death. Paris green, London purple, and white arsenic 

 are the most usual poisons. Grasshoppers, locusts, and 

 army worms are killed in this way. In some portions of 

 Texas they have the leaf-cutting ants, which attack 

 peach trees in great numbers and cut and carry off 

 nearly all the leaves. These ants do not eat the leaves, 

 but carry them into their underground nests and use 



Fig. 98. Cutworm and moth. After 

 Howard. Bureau of Entomology, 

 United States, Department of Agri- 

 culture. 



