548 EXPERIMENT STATION RECORD. 



The migratory habits of rats, with special reference to the spread of 

 plague, 11. H. Cbeel (Pub. Health Rpts. [U. &.], 30 (lUlo), No. 23, pp. 1679- 

 1685, fig. 1). — A study of the spread of rodent plague in New Orleans which 

 gave evidence that the dissemination of the infection was due to rodent travel 

 led to the investigation here reported. 



Two .series of experiments were conducted, the first with 179 rats (J/ms 

 norvegicus) , the second with 113 rats. After their ears had been marke<l for 

 identification they were released, the first in the central residential section 

 of the city and the second in the wholesale provision warehouse district. The 

 first rat of the first lot trapped at any considerable distance was taken within 

 60 hours at a distance of about one mile from the point of release, having 

 traversed 19 blocks and crossed a main traveled avenue, 150 ft. in width, the 

 travel having been above ground as there was no subsurface conduit. Within 

 two weeks a number of rats were retaken from points four miles distant from 

 the site where they had been released. It is pointed out that the section where 

 the second lot was released affordetl fairly ample harborage in the way of 

 wooden culverts, drains, and similar structures in the streets, as well as a 

 large quantity of foodstuffs, such as green vegetables, deposited in the gutters 

 and streets each day. As a result only 8 of this lot of 113 made any extensive 

 travel, although 40 of the lot of 179 made widespread excursions. 



" The migratory habits of wild animals are well known in a general way, 

 the phenomena being influenced by weather conditions, a local shortage in foo<l 

 supply, the appearance of an epizootic, or the presence of some natural enemy. 

 Self-preservation presumably is the motive. ... In addition to obtaining data 

 on rodent nugration the experiment furni.shed an index on the trapping effi- 

 ciency of the service force; 103 of the 179 rats in the first .series were recap- 

 tured during the following month and of the 113 In the second series 60 were 

 recaptured in 2G days." 



Insects and insecticides, C. P. Gn.LETTE and G. M. List (Colorado Sta. Bid. 

 210 (1915). pp. 5-55, figs. .}7). — This is a revision of Bulletin 114. previously 

 noted (E. S. R., IS. p. 101). 



The toxic values of the arsenates of lead, H. V. T.vbt.xr and H. F. Wilson 

 (■lour. Econ. Ent., 8 (1915). Xo. 5. pp. 481-^86). — Continuing previous work at 

 the Oregon Experiment Station on the two different arsenates of lead present 

 in the commercial material (E. S. R., 33, p. 801), data are presentetl relating 

 to the comparative toxic value of the two compound.s. 



"A comparison of the efficiency values shows that the lead hydrogen arsenate 

 in strengths of 2: 50 was quicker acting than the basic, but the results obtained 

 with the latter were satisfactory in that practically the same amount of foliage 

 was eaten in both cases. In strengths of 2:100 the difference in action was 

 greatly in favor of the lead hydrogen arsenate, but only a slight difference was 

 noticed in the amount of foliage destroyed. . . . Further comparison showed 

 that the lead hydrogen arsenate 2: 200 was more efficient than the basic 2: 100 

 and that the lead hydrogen arsenate 2 : 400 was more efficient than the basic 

 2: 200 in the protection of foliage.'' 



[Insect control], F. Sherman, Jr. (Bui. X. C. Dept. Agr.. 36 (191.5). Xo. 6. 

 pp. 67. fiflft. 10). — This bulletin, which deals with the San .Tos«5 scale and reme- 

 dies therefor (pp. 5-20), orchard spraying (pp. 27-50). and orchard jirotection 

 (l)p. 51-58). is a revision of a bulletin previously noted (E. S. R., 28. p. ,3.52). 



Some results of the introduction of beneficial insects in the Hawaiian 

 Islands, O. H. Swezev (.four. Econ. Ent.. 8 (1915), No. 5. pp. 450-457).— \ dis- 

 cussion of the results obtained from the introduction of parasites, particularly 

 those of leaf rollers, sugar cane leafhoppers. cane borers, and fruit fly. Mention 



