PAKASITE FLIES OF WHEAT MIDGE. 165 



There are other kinds of Parasites of nearly-allied 

 kinds, which we have not space to enter on here ; but 

 the general principle of preserving a useful amount of 

 them is so important that, though it is a very difficult 

 matter to protect them, it is as ivell to he careful about 

 setting on foot regular measures calculated to lessen 

 their numbers. 



It may be doubted whether, in regard to help from 

 parasitic insects, we do not suffer, rather than benefit 

 ■as much as is supposed, by great encouragement of 

 birds. We cannot tell accurately what amount of 

 the small Parasite Flies are taken as bird food, for 

 their small bodies are probably soon digested ; but it 

 appears reasonable to suppose that as we know some 

 birds take them, others also do so, and in this 

 way do the reverse of helping. I would not for an 

 instant suggest clearing away birds ; but it would be 

 well to bear in mind that the works of creation are 

 founded on a principle of order, and of relationship 

 of one part on another ; and if we use such power as 

 we may have to alter any detail, we are likely to 

 suffer. We have altered the amount of food for 

 insects by the enormous necessary increase in food 

 crops ; but it appears to me that to try to keep these 

 insects in check by calling in bird-help in legions, — 

 which grub up the plants to be protected, and eat up 

 the eaters of the insect foes, and likewise (when 

 insect food fails the many mouths) betake them to the 

 Wheat-ears, — is very much like bringing in the rats 

 to drive out the mice. 



The families of Wasps, Bees, and Ants are included 

 in another great section of this order, called the 

 Aculeata, because they, or most of them, are furnished 

 with a sting, much resembling in appearance, and 

 pain of application, a needle ; known in Latin as 

 Acus. 



These have been written on for so many years that 

 we need not enter on them at length ; but it is well 

 •to observe that the Hive Bees, the social Wasps, and 



