CHAPTER XXVII 

 INSECTS— INJURIOUS AND BENEFICIAL 



Much damage is done our field, garden, and orchard crops 

 every year by insects. It is estimated that more than three 

 hundred miUion dollars' worth of crops is destroyed every 

 year by them. However, we must not condemn all insects, 

 for all are not injurious. Some are quite useful and we do 

 ourselves injury when we kill them. 



The life of an insect is very interesting and may be divided 

 into four stages. The first is the egg state. Every insect is 

 developed from an Qgg; though under certain conditions 

 plant-lice and some scale insects are born alive. The second 

 stage is the larval or worm stage. After the egg hatches, the 

 insect exists for some time as a worm, eating the foliage or 

 roots or sucking the juices of the plant. During the time that 

 it is a worm, the insect grows larger and larger, and to accom- 

 modate its increased size it changes its skin one or more 

 times. The third stage is the resting stage. This is also 

 called the pupa or chrysalis stage. Some insects do not stay 

 in this stage very long, others do for several months. Every 

 one has seen the silken cocoons that some insects weave 

 around themselves when they go into the resting stage. 

 Many insects do not make a cocoon, but their skin hardens 

 and they rest quietly in that form for a time. When the insect 



comes out of its cocoon, or hard case, it is quite different in 



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