408 



approximately one-lialf control. The best control was by Niagara 

 dust sulphur, 85 per cent., plus Corona lead arsenate, 15 per cent., in 

 the form of a dust application. This material was also found to check 

 apple scab to a fair degree. 



Gillette (C. P.) & Beagg (L. C). The Migratory Habits of Myzus 

 rihis (L.), — Jl. Econ. Entmi., Cofword, N.H., x, no. 3, June 1917, 

 pp. 338-340, 1 fig. 



Myzus rihis is commonly found upon the leaves of various species of 

 Ribes, especially upon the red currant, and is also known to attack the 

 leaves of European black currant. Rocky Mountain wild currant 

 (R. aureum), and occasionally the gooseberry. It is known to migrate 

 from currant bushes in the middle of summer, but the alternate hosts 

 have not been determined. Myzus galeopsidis has been found on 

 Stadiys as a summer host in Colorado, and a similar louse was taken 

 upon Lamium and Stachys by Van der Goot, who thought the species 

 might be identical with M. ribis, but was doubtful, as his attempts 

 to transfer early summer forms to Lamium did not succeed. The 

 authors of the present paper have repeatedly transferred the migrants 

 from Ribes to Stachys and Leonurus, and the autumn migrants from 

 these plants to the currant ; they therefore assume that these two 

 genera at least can be accepted as summer hosts of Myzus ribis, L. 



LovETT (A. L.) & Robinson (R. H.). Arsenic as an Insecticide. — Jl. 



Econ. Entom., Concord, N.H., x, no. 3, June 1917, pp. 345-348. 



A series of experiments are described in which an endeavour was 

 made to find some inert material, easily obtainable in considerable 

 quantities at reasonable cost, which would absorb sufficient arsenic 

 from an arsenical solution to make the substance efficient as a spray, 

 and which would thus reduce the cost of arsenical sprays. For these 

 investigations, lamp-black and fuller's earth were used as absorbents 

 of arsenic from a water solution of arsenic acid. Tables are given 

 showing the killing efficiency of the various mixtures, the strength of 

 materials used and the resultant degree of burning. Lamp-black 

 proved impracticable under field conditions, the black colour apparently 

 increasing the degree of burning owing to absorbing heat. Mixtures 

 having fuller's earth as an absorbent caused comparatively little 

 burning, while equal dilutions of arsenic without any absorbent burned 

 up all the foliage. The results of one season's observations, both as to 

 toxicity for insects and as to amount of burning, indicate that there 

 are possibilities in the use of absorbents with arsenic, and further trials 

 are plamied on a larger scale for the coming season. If such a material 

 is found adaptable to commercial uses, it should reduce the cost of 

 arsenical sprays by about two-fifths. 



Davidson (W. M.). The Reddish-brown Plum Aphis {Rhopalosiphum 

 nym])}ieae, L.). — Jl. Econ. Entom., Concord, N.H., x, no. 3, June 

 1917, pp. 350-353, 1 fig. 



RJwpalosiphum nympheae, L., is widely distributed in the plum and 

 prune districts of California, but is generally confined to a few trees in 

 an orchard, so that the injury caused is at present negligible. The 



