21 



of their small number they cau be readily watched and easily treated, either by burn- 

 ing the webs or by spraying with an arsenical poison. I should think, then, that it 

 is an advantage to have a very few wild-cherry trees near an orchard and a disad- 

 vantage to have a large number. The eggs are so easily seen on the cherry-tree in 

 winter that the prnuing and burning of these is one of the best i)reventive meas- 

 ures.— [May 16. 1890.] 



The Horn Fly. 



The Horn Fly has made its appearance again in considerable numbers and is an- 

 noying our cattle greatly. I can apply the train-oil to the dairy cows in their stalls, 

 but it is exceedingly troublesome, not to say difficult, to apply it to the compara- 

 tively wild field cattle and steers. Can an emulsion be made of it, so as to apply it 

 to the cattle with our tree-spraying pumps? And if so, in what way is it best done? 

 It is impracticable in our large fields, many of them including woods, to apply lime 

 to the droppings, as recommended in the special bulletin on the Horn Fly, issued in 

 1889.— [H. M. Magruder, Charlottesville, Va., May 12,1890. 



Rei'LY. — Your letter of the r2th May has come to hand. There ought to be no dif- 

 ficulty in making the emulsion of train-oil with soap, so as to be able to apply it with 

 a spray pump ; but I am of the opinion that it will be difficult to apply in a spray 

 thoroughly enough to cattle iu the fields to keep the flies off for any length of time. 

 However, as you seem desirous of trying the experiment, I shall be very glad indeed 

 to learn the result. To emulsify the train oil satisfactorily it will only be necessary 

 to prepare it according to the inclosed formula, simply substituting train-oil for kero- 

 sene. In spite of your statement that it is impracticable in your large fields to apply 

 lime to the droppings it seems to me a great deal of good can be accomplished at just 

 this time of the year. If the flies are just appearing they will soou begin to lay their 

 eggs and the numbers of subsequent generations can be greatly reduced if only a por- 

 tion of the dung is limed. Are there not certain points in the field where the cattle 

 stand through the heat of the day and where the dung can be limed ? — [May 13, 1890.] 



A Jack Rabbit Parasite. 



I should like to call your attention to a parasite that infests the Jack Rabbits of 

 this country, and in view of the fact that the Australian Government offers a large 

 reward for the destruction of rabbits in that country it may be that this parasite 

 would be just the right thing. It occurs in the shape of a large lump on the back, 

 hips, and thighs. Upon examination it seems to be made up of innumerable small 

 transparent sacs, which are held together in rows. The lump gets larger and others 

 appear and finally the rabbit dies. If this parasite is unknown to scientific men I 

 would take pleasure in sending you specimens in alcohol or as you may direct. I 

 believe this country would be overrun with rabbits were it not for this parasite. 

 But it does not kill them all, and it may be that it does not kill them at all, but I 

 frequently find them dead from some cause. — [D. G. Sherrard, Burnet, Burnet 

 County, Tex., May 3, 1890. 



Reply. — I beg to acknowledge the receipt of yours of the 5th inst. There are sev- 

 eral species of true "Bots" which infest rabbits, although I am not aware that any 

 species is specifically confined to the " Jack Rabbit," nor am I at all certain that the 

 parasite which you mention is a Bot. The matter can be readily settled, viz., send 

 specimens in alcohol. Please see that the bottle is carefully packed in sawdust, and 

 if you will forward by express, all charges will be paid at this end. Please mark the 

 package with your name. — [May 13, 1890.] 



Supposed Bed-bugs under Bark of Trees. 



In No. 4, volume 2, Insect Life, page 106, regarding the "Bed-bug" (Acanthia 

 lectularia L.), I will say that I have seen the "bug" under the bark of the Cotton- 

 wood {Populus monilijera) in many places in the West, and more especially along the 



