ECONOMIC ZOOLOGY ENTOMOLOGY. 61 



" Additional experiments witli deep plowing and repeated disking made in 

 1909 sliowed in one case a decrease, due to the treatment, of 43 per cent in ttie 

 number of hills infested by ants and 18 per .cent in the number of ants in the 

 infested hills, and a decrease of 27 per cent in the number of hills infested by 

 root lice and of 9 per cent in the number of the root lice themselves. In another 

 case the number of hills infested by ants was reduced 71 per cent and the 

 number of ants in the infested hills S3 per cent, the number of hills infested by 

 root lice 8G per cent and the number of root lice in the infested hills Gl per cent. 

 The same experiment showed that deep disking with a 20-in. disk was much 

 more effective in diminishing the number of ants and root lice than was the 

 comparatively shallow disking of a 16-in. disk, the difference between the two 

 methods of treatment being 34 per cent and 48 per cent in the number of hills 

 infested by ants and aphids, respectively, and 13 per cent and 35 per cent in 

 the number of these insects themselves. It was incidentally shown by this 

 experiment that plowing to a depth of 4 in. does not sufficiently break up the 

 nests of the ants, but that about 85 per cent of them may be broken up by 

 plowing 6 in. deep, the remainder being at least broken into. 



" Observations made at night upon the movements of colonies of ants out 

 of plats treated as above, and across furrows surrounding them, showed 

 nearly two and a half times as many migrations from the plats deeply stirred 

 as from the check plat. Migration lines across furrows plowed through the 

 center of each of the plats a week after planting showed the amount of normal 

 underground movements of the ants at this time. Making due allowance for 

 this, it appears that the migration movement caused by the disturbance of 

 the ants in treated plats was more than, five times as great as is normal. 



" Plowing to a depth of 6 in. in a Galesburg field in 1910 dispersed 55 per 

 cent of the ant colonies in this field, and one disking after plowing dispersed 

 15 per cent more. Plowing in. deep, disking three times, and rolling once 

 increased the yield of the plat nearly 25 per cent, at a cost of 22 cts. a bushel. 

 One 20 in. disking followed by rolling gave all the advantages obtainable by 

 additional diskings. Fall plowing and one spring disking are much more effec- 

 tive than spring plowing with no disking, the latter containing about three 

 times as many ants and four times as many aphids as the former. 



" Change of corn ground to oats for one year and fall plowing of the oats 

 stubble gave a larger yield by 25 per cent than adjacent ground kept continu- 

 ously in corn, this difference being accompanied by a root louse infestation of 

 young corn on the oats stubble about one-tenth that found in com on old corn 

 ground." 



The gipsy moth, W. E. Britton {ConnecUcut ^tate 8ta. Bui. 186 {1915}, pp. 

 2J^, figs. 16). — A summarized account of this pest, particularly as relates to 

 Connecticut. 



Studies of the codling moth in the central Appalachian region, F. E. 

 Brooks and E. B, Blakeslee (U. 8. Dept. Agr. Bui. 189 {1915), pp. 49, pi. 1, 

 figs. 23). — This is a report of studies of the codling moth, commenced in the 

 spring of 1911 and continued for three successive years, which form part of 

 the investigations of this insect that have been carried on by the Bureau of 

 Entomology throughout the United States, including Arkansas (E. S. R., 21, p. 

 455), Pennsylvania (24, p. 256), California (25, p. 154; 28, p. 558), Michigan 

 (28, p. 60), and New Mexico (31, p. 252). The work was conducted at several 

 points in Virginia, West Virginia, and Maryland, comprising a difference in 

 latitude of 1° 40' and in altitude of about 3,100 ft., the most southerly and 

 least elevated station being at Charlottesville, Va., the most northerly at 

 Hagerstown, Md., and the most elevated at Pickens, West Va. 



