MASON AND LEFBOT. 7 



Again, many birds, entirely insectivorous, take more beneficial 

 insects than injurious or harmless ones. How can these be bene- 

 ficial ? The beneficial action in destruction of injurious and harm- 

 less insects is more than counterbalanced by the injurious action 

 in destruction of beneficial insects. Many birds will probably be 

 found to take harmless insects only. I consider a bird that feeds 

 on harmless insects to be beneficial. He keeps a check on undue 

 proportion of these insects, and therefore prevents to some extern 

 any likelihood of such insects making sudden inroads on crops, 

 which might occur under abnormal or other climatic conditions. 

 Again, a bird may consume vast quantities of injurious insects and 

 yet by carrying eggs and larvae from one place to another, act as 

 the direct agent for spreading the attack of some insect pests. This 

 is not beneficial action. 



Agriculturally all insects fall under one of three definitely 

 marked headings : 



I. Beneficial and Useful 



1. Act as checks on undue multiplication of other insect and 



plant life, which is injurious or likely to be injurious 

 to agricultural interests, to stores and plant life. 



Among these are included the Lady-bird beetles (Coccinellidce) 

 which control to some extent the attacks of Plant lice 

 (Aphidce) ; Ground-beetles (Carabidce) and Tiger-beetles 

 (Cicindelidce) carnivorous. The Ichneumonidce and 

 other parasitic Hymenoptera. Many flies (Tachinidce, 

 etc.), also parasitic on caterpillars and other injurious 

 insect life. Dragon-flies (Odonata), Ant-lions (Myrmeleo) 

 and Lace- wing flies (Chrysopidce), all carnivorous. 



Some Hemiptera or bugs suck out juices from caterpillars, 

 etc., and kill them. 



2. Play a considerable part in the fertilization of flowers. 



Bees (Apidce), and possibly many other forms. 



3. Live on animals and plants to the benefit of their ho$1s, 



Mallophaya (?) 



