86 AGRICULTURE. 



3. The adult insect usually has two large, compound eyes, 

 that is, eyes made up of many parts. The antennae, or 

 " feelers," are attached to the head. Some persons think that 

 insects hear by means of their antennae. 



4. Insects breathe, not through the mouth, but through small 

 holes or openings along their sides. These are called " spir- 

 acles " and are connected with air tubes passing through the 

 body. 



5. As a rule insects pass through three forms after coming 

 from the eggs, known as : first, the larva (caterpillars, grubs, 

 slugs, maggots, etc.) ; second, the pupa (called chrysalis and 

 nymph in certain forms) ; and third, the imago or perfect or 

 adult insect (butterflies, moths, beetles, flies, etc.). 



6. Insects are kept in check by nature in various ways. They 

 destroy one another; for instance, the lady-bird beetle, the 

 ground-beetle, the tiger-beetle, the aphis-lion prey upon other 

 insects. Toads and lizards devour large quantities of insects. 

 Many birds feed upon insects almost entirely, and are hence 

 called " insectivorous birds." 



7. Insects lay eggs when in the imago or perfect form, but the 

 damage to plants is done principally when in the larval form. 

 The imago or adult insect is full grown when it comes from 

 the pupa. 



8. Insects injure plants either by biting and eating the 

 foliage and other living parts, or by sucking their sap. Biting 

 insects, such as cutworms and grubs, may be destroyed by 

 placing poison (Paris green, etc.) on the plants. Sucking 

 insects, such as plant-lice, are destroyed by dusting the plants 

 with insect powder or by spraying them with an emulsion of 

 kerosene and soap thereby closing up the breathing holes of 

 the insects. 



9. Where the insects of field crops cannot be destroyed by 

 spraying, the best practice is to keep the fields and fence 

 corners clean and free from weeds and rubbish, to thoroughly till 



