176 NATURE TEACHING. 



The adult insects have two membranous wings, 

 and the mouth is formed for suction and not 

 for biting. 



7. Reference is made here only to those 

 classes of insects which are commonly met 

 with in gardening operations. Ticks and spi-~ 

 ders are not insects, but are placed in a class 

 by themselves. They are distinguished from 

 insects by the fact that when full grown they 

 have eight jointed legs whereas insects never 

 have more than six. 



REMEDIES. 



1. In order to limit the damage done to 

 crops by injurious insects various steps may be 

 taken ; first of all the eggs of butterflies and 

 moths when seen upon leaves should be des- 

 troyed, and the caterpillars should be picked 

 off and killed. When these remedies are 

 inapplicable various insecticides may be dusted 

 or sprayed upon the plants attacked. An 

 account of these is to be found in a pamphlet 

 recently issued by the Commissioner of the 

 Imperial Department of Agriculture for the 

 West Indies entitled General Treatment of 

 Insect Pests. 



2. Many caterpillars are kept in check by 

 being attacked by 'other insects which lay their 



