344 



its beak or proboscis extends through the epidermis to the sap be- 

 neath. Therefore in the latter case we must treat the insect itself 

 and not its food. 



INSECT CHANGES. 



Just as the injurious insects of the orchard or farm can be 

 divided into two great classes as regards their food habits, that is, 

 chewing insects and sucking insects, so also they can be divided 

 into two great classes or divisions as regards their process of de- 

 velopment. All insects undergo during their developmental period 

 remarkable changes of structure, form and habits. With some, as 

 the moths and butterflies, the beetles and the true flies, the change 

 of form is complete. These insects after hatching from the egg 

 have three distinct stages of development, — the young or larval 

 period, commonly called the caterpillar, grub or maggot ; the 

 pupa, a period of transformation ; and the adult winged form. 

 The young or larval stage is one of growth and it is during this 

 time that the plant feeding species often do their greatest injury. 



With those insects not making a complete change of form dur- 

 ing their development, the young on hatching from the egg re- 

 semble the parent, in possessing the three distinct divisions of 

 the body, three pairs of legs and other characteristics of the adult 

 insect, with the exception that they are smaller in size, lack wings^ 

 and are otherwise immature. 



INSECT CONTROL. 



Insect control may be classified as follows : Direct ]\Ieasures^ 

 Cultural Methods, Sanitation, Natural Enemies, and Quarantine. 



Direct measures implies going into the orchard with the neces- 

 sary apparatus and compounds and actually destroying the in- 

 jurious insects in numbers sufficient to reduce their injury to a 

 minimum. 



Insecticides for biting insects {stomach poisons) : Insects that 

 bite ofif and swallow the portions of plants upon which they feed 

 would likewise take into their systems any poison that might be 

 placed upon the surface. Tlierefore, in combating an insect be- 

 longing to this class, that is. those actually chewing or gnawing 

 into the foliage, the idea is to cover the surface with a poison 

 harmless to the plant but sufficient in strength to kill the insect 

 when taken into its stomach. The insect killing substance, or 



