66 



female ate 212 square feet of lettuce leaves from tlie time it hatched 

 until it pupated. One male ate 110 square feet of lettuce leaves during 

 the same period. Dr. Gray gives the leaf surface of the Washington 

 elm in Cambridge as 200,000 square feet. That represents both sides 

 of the leaf. Taking 100,000 square feet, if 179 females are allowed to 

 lay their eggs, and the eggs hatch, and the cateriullars reach maturity 

 without any accident, they would be sufficient to defoliate that tree. 

 And yet in Medford I found trees that were literally yellow with the 

 egg clusters. 



We tried experiments in assembling, with a view of ascertaining 

 whether it would be possible to destroy all the males in a given region, 

 so that no fertilized eggs would be laid. We took a somewhat isolated 

 colony and placed the virgin females in traps or cages. The cages had 

 gauze over the sides, so that a draft of air passed through and the 

 odors would be carried away, and the males would lly up from the lee- 

 ward side and would come in contact with the "sticky fly i^aper" on 

 the sides of the cage, and would be taken the next morning and 

 destroyed. We took enormous numbers of males in that way. It would 

 seem as though the females would lay unfertilized eggs, but, strange as 

 it may seem, they were found to be fertile, and we gave it up as an 

 impracticable thing. It was interesting and settled the question to my 

 mind. We found that the males would mate with four females in suc- 

 cession, so it was not necessary to have as many males as females. 



The people of the State of Massachusetts saw they had a stupendous 

 undertaking on their hands, and I think you will all admit that a mag- 

 nificent fight has thus far been made. The State has already appro- 

 priated $525,000, and the last appropriation is not yet all expended. 

 We in Massachusetts are not the oidy ones interested in this matter. 

 Every citizen of the United States is interested. In Europe it extends 

 as far north as Riga; occurs abundantly in Moscow, but not at St. 

 Petersburg. It occurs south in the islands of the Mediterranean; is 

 abundant on the north coast of Africa; occurs in southern Siberia as 

 far as the Amoor; and my colleague. Professor Brooks, found this 

 insect in Japan — one of the Japan species — and I infer from his reports 

 that its habits there are much the same as here. 



I have been severely criticised because I have not favored the impor- 

 tation of parasites. I may be wrong. If I have made a mistake I 

 myself must bear the responsibility. I never dealt with abler men 

 than those of this committee. If there is any credit it is due to them, 

 and if there have been any grave mistakes during the past few years the 

 responsibility lies with me. The committee has considered carefully 

 every suggestion that I have made. I have not made any rash or 

 hasty statements, but have given them advice as to the methods of 

 procedure, and they have almost invariably followed my advice. I felt 

 that there was a great responsibility upon me, and I asked them to 

 invite entomologists from other States to go over the territory and 



