346 Forty-fourth Report on the State Museum 



Carbolized Plaster Preventive. 



Plaster of Paris has frequently been used to prevent insect depre- 

 dation^ but it is doubtful if it would be more efficacious for this 

 purpose, when applied to fruit trees, than ashes or road dust. From 

 some experiments in protecting plum trees from curculio attack, 

 carbolized plaster, made by combining one pint of crude carbolic acid 

 with fifty pounds of plaster, has shown such beneficial results that 

 the method merits additional trials. It may prove a valuable pre- 

 ventive of the depredations of the rose-bug, Macrodactylus suhspinosus, 

 from which, as yet, we know of no satisfactory m«ans of protection. 



Study of the Rose-bug. 

 The recent working out of the life-history of this great pest of the 

 fruit-grower and florist, by the Entomological Division at Washing- 

 ton, will, it is hoped, when published, aid materially in operations 

 against it; but I have long thought that our best success in contend- 

 ing with it is to be found in the study of its particular breeding 

 grounds. It is known to be a local insect, appearing suddenly in 

 immense numbers, in particular localities only, and there is, therefore, 

 reason to believe that it has its particular breeding grounds. In one 

 instance, at least, such a source for it has been known and observed 

 for many years. Mrs. Lucy G-. Chrisman, of Chrisman, Va., with 

 whom I have exchanged several letters on the subject, informs me 

 that year after year the rose-bugs may be seen coming in myriads 

 from a bush-covered, swampy or marshy soil, of sand that is always 

 wet, and which had, evidently, in former years, been a bend in the 

 river, now cut off by a change in the channel. They are annually 

 true to their appointed time of appearance almost to a day, and true 

 also to their line of flignt, which she has kindly mapped out for me, 

 and represents as being in a body about five hundred feet broad, moving 

 up the old river bed the first day as far as a church indicated in her 

 sketch, about a mile from the swamp, and flying quite low. The 

 second day they rise higher in their continued flight, spreading some- 

 what, and reaching certain points beyond (indicated) in one, two and 

 three days thereafter. I hope, later, to compile from "Mrs. Chrisman's 

 letters the interesting observations made by her and gathered from 

 her friends, of the breeding ground, flight, limitation to sandy soil, 

 feeding and other habits, which she has very kindly given to me. [*] 



In the necessarily hurried preparation of my Annual Report for 

 the last year, which was handed in for printing in December last, 



[* An admirable study of the Rose-bug has since been made by Prof. Jno. B, Smith, of 

 the New Jersey Agricultural College Experiment Station, which has been published as 

 Bulletin No. 82, July, 1891, of that station : pp. 40, figs. 10.] 



