3o8 INSECTS 



natural balance by introducing the natural checks as 

 well, and beyond that he relies on his own efforts. 



We have learned to take advantage of the weak 

 points in the life cycle of a troublesome species, and 

 we know that there is at least as much in the proper 

 application of insecticides as in the insecticides them- 

 selves. As there is a continuous specialization in the 

 raising of crops, so each grower learns to deal with the 

 pests of that crop by experiment and observation. 



It is beginning to be realized that numbers of speci- 

 mens are not a measure of the difficulty in dealing 

 with pests. Mosquitoes are abundant enough in exam- 

 ples, but their Hfe cycle is simple and the methods of 

 control are obvious. The old cry "it can't be done" 

 has not even yet ceased, in the face of the results ob- 

 tained in Cuba, Panama, and New Jersey. And yet, 

 after all, it is simply a matter of dealing with many 

 breeding places in the same way, and when a problem 

 is reduced to a mere matter of amount, it is a matter 

 of time and dollars only to get it done. 



Flies are even more universally distributed than 

 mosquitoes, and from the sanitary standpoint yet 

 more dangerous; but even they will not escape man's 

 efforts at control. The campaign has been already 

 begun and no doubt it will be continued until practical 

 measures for checking fly development are universal. 



To one in the forefront of the battle progress some- 

 times seems distressingly slow, and results small out 

 of all proportion to the efforts made; but, after all, 

 a review extending back a decade or two shows that 

 neither the entomologist nor those for whom he has 

 labored need be ashamed of the advances made. At 

 all events the importance of insects in their relation to 

 man has come to be fully realized. 



