ECONOMIC ZOOLOGY — ENTOMOLOGY. 545 



dermium pinastrl, which is said to be becoming very destructive to white pines 

 and otlier species in the western National Forests, and also a needle cast of 

 larch which is assuming epidemic form in the Priest River Valley. 



ECONOMIC ZOOLOGY— ENTOMOLOGY. 



Experiments on the destruction of voles (Bui. Mcii.s. Off. Rrnscig. Affr. 

 [Paris], 12 U91S), No. //, pp. 399-401; o/>.s. in Jour. Bd. Agr. [London], 20 

 (1913), No. 7, p. 621). — The damage caused by voles in the eastern districts of 

 France in 1912 led to an appropriation of 250,000 francs for use in combating 

 them. Since the use of Danysz virus was not attended with very satisfactory 

 results experiments were made with the commercial virus, known as " Ratin," 

 on 24 plats covering a total, area of 2.3 acres, distributed over a badly infested 

 area of 30,000 acres. 



On these plats 321 dead and 178 living voles were found, or a mortality of 

 about 70 per cent. Taking into consideration the rate of reproduction of the 

 voles it is estimated that a mortality of 90 per cent must be attained before 

 the treatment can be considered satisfactory, and this result was obtained on 

 but 4 plats. The virus was most effective on pasture and old stubble. It is 

 concluded that while Ratin may be classed among the preparations useful in 

 the extermination of voles, its general employment can not be recommended. 

 The experiments confirmed previous experience in that treatment on a large 

 scale led to the emigration of the voles. 



The relative lengths of the larg-e and small intestines in rodents, T. D. 

 A. CocKERELL, L. I. MiLLEE, and M. Printz (Proc. Biol. Soc. Wash.. 26 (1913), 

 pp. 205-207).' — This paper reports the results of an anatomical study of six 

 species of rodents. 



Five important wild duck foods, W. L. McAtee (U. S. Dept. Agr. Bui. 58 

 (1914), pp. 19, figs. 16). — Supplementing information relating to wild rice, wild 

 celery, and poudweeds, previously noted (E. S. R., 25, p. 757), studies are re- 

 ported on 5 other important phmt foods of wild ducks. 



The tubers of the Delta duck potato (Sagittaria platyphylla) , known to the 

 hunters of the Delta and other parts of Louisiana as wild potato or wild 

 onion, were found to furnish 70 per cent of the food of canvasbacks collected 

 and more than 65 per cent of the food of mallards, and the pintail was also 

 found to feed upon them. This plant is thought to be hardy anywhere in the 

 southern half of the United States, and may be proved to be so farther north. 

 The second duck food considered is the wapato, represented by the 2 species, 

 8. latifolia and ;Sf. arifolia. The former species is found from the Atlantic to 

 the Pacific coast, its range covering practically the whole United States, while 

 the latter is confined to States from Michigan and Kansas westward. In the 

 course of the studies, the Biological Survey has found various parts of Sagit- 

 taria plants in stomachs of the following species of waterfowl : Mallard, wid- 

 geon, green-winged teal, blue-winged teal, spoonbill, pintail, canvasback, little 

 bluebill, ruddy duck, Canada goose, and whooping swan. The remaining 3 

 duck foods discussed are the chufa (Cyperus esculentus), wild millet (Echi- 

 nochloa crus-galli), and banana water lily (Nympliwa mexicana). In the dis- 

 cussion of the plants directions are given for their propagation. 



Report of entomologist, A. F. Conradi (South Carolina Sta. Rpt. 1913, pp. 

 20-24). — This report consists mainly of a brief discussion of the progress of 

 two Adams Fund projects, the first, that of the relation of temperature and 

 moisture to insect activity; and the second, that of the slender wireworm of 

 cotton and corn. 



