458 EXPERIMENT STATION RECORD. 



injurious; potato beetles, for which arsenate of lead is recommended; 

 a tortoise beetle ( Coptocycla clavata), a new pest reported from Decker- 

 town in June, where it was eating off potato stalks; rose chafers, which 

 seem to be on the increase; Leeanium tulipiferce; root web worms; 

 Crioceris 12-j)unctata; cabbage worms ; sawtlies; Selandrice caryce; bag- 

 worms; codling - moths; plum curculio; the round-headed apple-tree 

 borer; pear blister mite; pear slugs; fig eater (Allorhina nitida); 

 Procris americana; and Monahammus titillator. 



A study was made of Paris green as an insecticide. Samples were 

 obtained from a large number of firms, and analyses made which 

 showed that they ranged in arsenious oxid from 41.54 to 08.50 per 

 cent. Variations were found even in different samples from the same 

 manufacturer. Explanatory letters were received which, though not 

 directly so stated, admitted the possibility of a variation of 15 percent. 

 This was not considered by the firm from which the letter came to be 

 worth considering from a practical standpoint, but from this statement 

 the author differs, stating that the "difference of even 10 per cent of 

 arsenic may make all the difference between an effective and an ineffect- 

 ive application." From obtainable facts it appears that Paris green 

 even under the best conditions varies greatly in the percentage of 

 arsenic and that it may be present either as an arsenite or as an arsen- 

 ate. Difficulties increase with the size of the quantities manufactured 

 so that a difference of 25 per cent may exist in the absolutely urn adul- 

 terated product. Hence it follows that the material as used by farmers 

 is found to be unreliable and the results inconsistent. As an alterna- 

 tive the use of arsenate of lead is suggested. The formula given for 

 it is 4 oz. arsenate of soda and 11 oz. acetate of lead dissolved sepa- 

 rately and then mixed. The resulting solution is to be added to 100 

 gal. of water for most insects, to 80 gal. lor more resistant insects, 

 and to 50 gal. for potato beetles. This insecticide is strongly recom- 

 mended. 



Experiments were made with emulsion sprayers in which the emul- 

 sion was obtained by mechanical means, which developed considerable 

 variation in the degree of reliability. The Success Emulsion Sprayer 

 was found to be wholly unreliable with mixtures in the proportion of 

 1:20, which proportion was actually never obtained in the spray, the 

 proportion ranging all the way from 1:100 to 1:15. Mixtures at the 

 rate of 1:15 exhibited much less variation, the spray showing from 

 7.3 to 10.5 per cent of kerosene. At the rate of 1 : 10 and 2:10 the 

 results were practically uniform. 



Experiments were also made with kerosene, which are reported in 

 considerable detail. The general conclusions have already been given 

 in a preliminary bulletin (E. S. R., 7, p. 515), as were also the author's 

 conclusions resulting from experiments with dendrolene and whale-oil 

 soap, and from his study of the San Jose scale; but it may be noted in 

 regard to the last insect that the author now finds it simpler to make a 

 list of the plants that the insect does not attack rather thau those 



