206 ENTOMOLOGICAL SOCIETY 



" This amount, therefore, at the end of 30x3 days (or 20 X X 5) would not 

 be less than the fifteenth power of 210, which is almost impossible to 

 express in figures. 'There would be room in the world for nothing else 

 but Aphides ! ' Truly, ' Nature is most wonderful in small things.' " 



These estimates, given above, are founded upon mathematical 

 exactness and cannot be refuted. But you will say : "If this is so, 

 why do not our Aphides increase and become more of a pest than 

 they are to-day?" I reply: Because of their parasites. Most 

 of our fruit trees and vines the apple, the peach, the orange, 

 the grape, watermelon, etc. and our more important field crops, 

 such as cotton, wheat, corn, etc., have distinct species of Aphides, 

 which destroy annually thousands of dollars' worth of these prod 

 ucts, but which, fortunately, are more or less kept under con 

 trol by their natural enemies these parasitic Hymenoptera and 

 other predaceous insects. 



From the orange Aphis in Florida, I have reared five distinct 

 species of parasites ; from the cotton Aphis, three or four ; 

 from the wheat Aphis seven or eight ; from the corn Aphis four 

 or five; and from other Aphides parasites in like proportions. 

 Fourteen years ago, from three or four large orange leaves taken 

 from an orange tree in my yard and badly infested with the 

 orange Aphis, I reared between three and four hundred specimens 

 of a parasite, and a careful examination of the leaves after 

 wards showed that every Aphis had been parasitized. Thou 

 sands of these little parasites were found running about on my 

 trees, and within a very brief period after their appearance my 

 trees were comparatively ree from the pest. 



These are only a few instances out of hundreds that could be 

 cited in illustration of the benefits derived from our Hymenop- 

 terous parasites. 



It would be well here, also, to draw attention to another side 

 of this important question of parasitism, that is, to the introduc 

 tion of the exotic, natural enemies of such of our insect pests as 

 have been imported from foreign countries. Scarcely any 

 attention at all has been given to this side of the question, although 

 lately the subject has been agitated aiid some efforts are now 

 being made towards its accomplishment. Let me urge, there 

 fore, upon all those who are in a position to influence action 



