454 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



Data proving the effectiveness of these home-made miscible oils 

 have already been published by Messrs. Yothers and Grossman (6 to 

 9) and have been corroborated, if corroboration were necessary, by 

 the senior writer during February and March, 1912, when he had tem- 

 porarily resumed field charge of the investigations, and was assisted 

 by Messrs. Wooldridge, Strickland and Rutherford. The data secured 

 at this time merely emphasized the dependableness of Mr. Yother's 

 formulae, and various modifications of them. Sprays containing from 

 J per cent to 3 per cent oil were used without injury to foliage. It was 

 rather surprising to find that sprays containing i per cent and \ per 

 cent of oil, made according to Formula IV of Mr. Yothers (7) were 

 very effective, and it seemed probable that strengths less than the 

 1 per cent of oil recommended might be used profitably, particularly 

 during the summer. Thus on 55 leaves picked from trees sprayed on 

 February 27 with | per cent oil and known to have been hit by the 

 spray, 98.4 per cent of 5,040 pupae were killed; while from two collec- 

 tions of leaves picked promiscuously from the trees which were sprayed 

 at the same time and with the same strength of oil, 98.1 per cent of 

 1,972 pupae found on 41 leaves and 98.7 per cent of 6,897 pupae on 100 

 leaves were killed. 



The purpose of this article is not so much to call attention to the 

 effectiveness of home-made miscible oil sprays recommended by the 

 Bureau, as it is to present certain data secured by the writers during 

 the summer of 1910 which form a basis for comparison between these 

 sprays and those made of fish oil soap. The results are based upon 

 work with a proprietary miscible oil then on the market and a good 

 fish oil soap. An analysis of the miscible oil made by the federal 

 Bureau of Chemistry at the request of Mr. C. L. Marlatt, in charge of 

 the Florida investigations, proved it to be practically the same as the 

 home-made emulsions recommended later by Mr. Yothers. The 

 analysis is as follows: specific gravity at 20° C, 0.9123; unsaponi- 

 fiable oils (mineral oils), 63.24 per cent; fatty acids (from soap), 5.61 

 per cent; sodium oxid (Na20), 0.63 per cent; water and undetermined, 

 30.52 per cent; rosin oil not present. 



So far as the writers are aware, no data have been published on the 

 effect of summer showers upon the eflaciency of insecticides in Florida. 

 During the summer of 1910 a large amount of such data were secured 

 which, in a greatly abridged form, is presented in Table I. 



The complete data are on file. Each percentage recorded in Table 

 I is an average of from three to seventeen similar averages, each in 

 turn based upon an examination of over a thousand larvae and pupae. 

 At least 210,000 larvae and pupae were examined. 



The data indicate that the miscible oil sprays are scarcely affected 



