ECONOMIC ZOOLOGY ENTOMOLOGY. 753 



in combating the locust. Part 4 (pp. 387-398) discusses the results which have 

 been obtained in Argentina, Colombia, Cyprus, and Algeria. Part 5 (pp. 

 399-407) deals with the organization of the worlc 



The destruction of locusts in Algeria by Coccobacillus acridiorum, E. 

 .Seegent and A. Lh^ritier (Ann. Inst. Pasteur, 28 (1914), No. .{, pp. JiOS-419, 

 figs. 2). — The authors report having succeeded in increasing the virulence of 

 cultures of C. acridiorum for the Algerian locust {Sfauronotus inaroccunus) 

 until the virus will cause death in about four hours. There appears to be 

 some doubt as to whether the disease will spread sufficiently rapidly to pro- 

 duce results of practical value and further experiments will be carried ou. 



The oat aphis, J. J. Davis (^7. 8. Dept. Agr. Bui. 112 (1914), PP- 16, figs. 9).— 

 The oat aphis (Aphis avenw) is said to be the most widely distributed and 

 most common over its area of distribution of the three important plant lice 

 attacking wheat and oats above ground, and second only to the so-called green 

 l»ug (Toxoptcra graminum) in importance as a wheat pest. This aphidid was 

 introduced into the United States previous to 1851 in which year it was recorded 

 by Fitch. While it has never been considered a pest of great importance, ob- 

 servations would lead to the belief that it is worthy of more serious con- 

 sideration. 



It is found in all parts of Europe as well as in most of the States in this 

 country and has been recorded from a large number of plants, particularly the 

 grasses. The author presents a summary of its life history, habits, natural 

 checks, remedial and preventive measures, etc.. based upon the literature 

 and experiments and observations by agents of the Bureau of Entomologj- 

 of this Department. 



The winter is passed in the egg stage on apple and related trees or as wingless 

 females. In the spring the progeny from the eggs hatching on apple migrate to 

 grasses and grains. From September to November the migrants return to the 

 apple where several forms are produced and eggs laid; others remain on grasses 

 or migrate to fresh grass hosts, passing the winter as viviparous females. 



The species is freely attacked by various parasitic and predaceous enemies 

 which doubtless are responsible for the usual control of this pest. As in the 

 case with the spring grain aphis or gi-een bug, it is practically impossible to 

 control the oat aphis after it has once gained much headway in numbers and 

 diffusion, but by proper precautions it is possible to prevent serious outbreaks. 



Walnut aphids in California, W. M. Davidson (U. 8. Dept. Agr. Bui. 100 

 <1914), PP- 48, pis. 4, figs. 18). — This is a detailed report of studies of the life 

 history and habits of aphidids commenced eax'Iy in the year 1911 and continue^l 

 until the summer of 1913, largely at Walnut Creek, Cal. The studies relate to 

 the European walnut aphis (Chromaphis juglandicola) which alone infests 

 walnuts of commercial value grown in California, and two native species found 

 to be pests on native walnuts that are much used for stock on which to graft 

 the European or Persian nut, namely, the American walnut aphis (Monellia 

 varyw) which attacks the eastern black walnut (Juglans nigra), and the little 

 hickory aphis (M. caryella) which attacks the California black walnut (J. 

 calif ornica) . 



" In general the aphidids inhabit the underside of the leaves, but those of 

 the second, third, and fourth generations often attack the nuts, sometimes 

 seriously dwarfing them. . .-. When infestation on the leaves and nuts is 

 severe the vitality of the infested tree is impaired. The aphidids excrete a 

 sweet, gummy, transparent substance much sought after by ants, and in this 

 thrives a black sooty fungus. This blacks fungus often covers the upper sides 

 of the lower leaves and the upper part of the nuts, thereby interfering with the 



