December 6, 1907] 



SCIENCE 



775 



portance; there have been important de- 

 velopments in methods; there have been 

 important discoveries in the life histories 

 of many species, leading to better measures 

 of control; there have been important 

 widenings of the field in many directions. 

 Only a few of these can be mentioned at 

 this time, and perhaps those chosen will 

 not, after all, be the most important. 



The demonstration work in connection 

 with the cotton boll weevil has been men- 

 tioned, and this in itself is an important 

 new factor in our work. It seems to be 

 not enough to tell a man that he can ac- 

 complish certain results by doing certain 

 things ; to establish perfect confidence it 

 is necessary to prove this, and to prove 

 it not by laboratory work, but by field 

 work, and by field work on a large scale. 

 The first demonstration work of this char- 

 acter was probably that carried on by Mr. 

 C. B. Simpson for the Bureau of Ento- 

 mology in the work against the codling 

 moth, in Idaho, in 1902. Here a lai-ge 

 commercial orchard was treated according 

 to the most approved method, and a check 

 orchard was left untreated. The results 

 were exhibited to apple-growers in the au- 

 tumn from the states of Idaho, Oregon and 

 Washington, and the demonstration was so 

 perfect as to induce a wide-spread adoption 

 of the methods used. In Texas and 

 Louisiana this demonstration work was car- 

 ried on at first by the Bureau of Ento- 

 mology, and later, after the methods were 

 shown to have been sound, by the Bureau 

 of Plant Industry, and upon a very large 

 scale. In the same way, during the sum- 

 mer of 1906, cooperative work against in- 

 jurious insects and fungus diseases of fruit 

 orchards was carried on by these two bu- 

 reaus in Nebraska, and during the present 

 summer this work is being repeated in 

 other states. The value of this demonstra- 

 tion is very great, and as before stated, 

 introduces a new element into the work. 



The international work with parasitic 

 and predatory insects referred to in my 

 previous paragraph is of course suggestive 

 of what may be done with parasites of 

 injurious species in a single country like 

 the United States, which is of broad extent, 

 and in which the climatic and crop condi- 

 tions vary so considerably. 



The Hessian fly, for example, that great 

 destroyer of wheat, has in certain seasons 

 and in certain localities parasites which 

 reduce it to a minimum, but it has been 

 shown that in the spring of certain years 

 these parasites wUl be competently abun- 

 dant in one region and practically absent in 

 another. Advantage has been taken of this 

 fact by Professor P. M. Webster, of the 

 Bureau of Entomology, and his corps of 

 assistants, to study and import from these 

 regions of parasite abundance, parasitized 

 puparia of the Hessian fly into regions 

 where the parasites upon actual examina- 

 tion have been found to be absent. Dur- 

 ing the present season, early in spring, 

 two early planted experimental plats, at 

 Lansing, Mich., and Marion, Pa., were very 

 seriously attacked by the Hessian fly, but on 

 full examination carefully made at a later 

 date, 90 per cent, of the puparia were 

 found to have been stung by a parasite of 

 the genus Polygnotus and to contain its 

 developing larvaj. A field of wheat near 

 Sharpsburg, Md., was found to be infested 

 by the fly, and examination indicated the 

 absence of the parasite. On April 8, a 

 large number of the parasitized puparia 

 from Marion, Pa., were brought to Sharps- 

 burg, and placed in the field. On July 8 

 an examination of the Sharpsburg field 

 showed that the parasites had taken hold 

 to such an extent that of the large number 

 of puparia taken and brought to the labora- 

 tory at Washington for examination, not 

 one was found which had not been para- 

 sitized. This is the most striking example 

 of the kind which has yet been recorded, 



