PARASITES IN CEREAL AND FORAGE CROP PRODUCTION. 99 



cutworms to be attacked and eaten by their black enemies. Sometimes 

 it is clear that a serious attack of cutworms is prevented or decidedly 

 lessened in this manner. I distinctly remember, years ago, when 

 there was a severe outbreak of the grain aphis Macrosiphum granaria 

 Buckton in Indiana. After the wheat in badly infested fields was 

 harvested and in the shock, standing with one of these shocks between 

 me and the late afternoon sun I could see the emerging parasites 

 swarming in the air just about and above the cap sheaves. A farmer 

 might see them, but to him they would be nothing but "' pissants." 

 There is hardly an entomologist who has attempted to rear adult 

 insects from the larvaj Avho has not failed again and again by reason 

 of the i^resence of parasites. 



Now, I wish to submit that the causes and effects in all of these 

 phenomena are always present; whether they are observed or not 

 does not in the least alter the sitiuition. The more light we can get 

 on the actions, habits, and life histoiy of parasites the better we shall 

 be able to utilize their force in applied agriculture. The forces of 

 Niagara Falls ran to waste for ages because no man understood how 

 to conserve and apply this power. The forces of insect parasitism 

 are, clearly, not all going to waste in this manner; but we are too 

 ignorant of this force or Iioav best to apply it in agriculture to derive 

 more than the crude benefits that naturally follow its primitive influ- 

 ences. HoAv much might this power be improved and directed if we 

 only understood how to do it ! To the ordinary farmer, at the present 

 time, it apparently makes little difference whether the development 

 of a parasite is polyembryonic or otherwise ; whether it is dimorphic 

 or not. But we can never hope to put him in the way of deriving the 

 greatest benefit from the interaction of parasites and hosts until we 

 have sifted this matter over and to the bottom. Indeed, we shall not 

 know ourselves how to search for and control this immense, natural, 

 powerful element until we have done this. In the past w^e have per- 

 haps been too much like the medical practitioner, who gave his patient 

 not the treatment that he should have had for his well being, and it 

 might even be detrimental, but that which tasted best and was the 

 most i^leasing. The patient, in return, eulogized the doctor, paid him 

 a round fee, and told him what a great man he was. which was, of 

 course, sweet and pleasing to that sort of a man of pills and capsules. 

 There has been altogether too nuich of this interpolated into agricul- 

 tural science already, and some one, perhaps at the risk of becoming 

 temporarily unpopular among the unscientific, must accept the trust 

 and work out such obscure problems from the beginning, securing 

 for those who wva\ or may not understand the best and most that is 

 to be derived from a knowledge to be gained only by thorough pains- 

 taking investigations. 



