986 NEW YORK STATE MUSEUM 



and it was also not entirely effective in killing the scale. Its use can not 

 be recommended at present. 



Crude petroleum. The 20% mechanical emulsion of this substance 

 easily stands as one of the most satisfactory sprays to be used on dor- 

 mant scale insects in early spring. The trees appear to be uninjured by 

 the insecticide, though possibly a little retarded, while a large proportion 

 of the scales are killed, and on some trees it would appear as though 

 every one had been annihilated. A study of the preceding records will 

 show that all trees treated with this substance and having on them, July 2, 

 enough young to warrant the designation of "somewhat abundant or 

 numerous " were badly or very badly infested with this scale to begin 

 with. That is, each of these trees was literally incrusted in places with 

 the scale, and in the case of those classed as " very badly infested," the 

 incrustation was of considerable extent. It was found to be very 

 difficult to throw enough oil on these places to kill the scale and at 

 the same time avoid injuring the trees. Then some allowance must 

 be made for imperfections in spraying. It is within possibilities 

 to cover a tree with a nearly uniform coating of an insecticide, 

 but in actual practice this is rarely done. It will also be noticed 

 that in spite of some scales being found in early July, they are far 

 from abundant a month later. The infestation is still kept down in 

 early September, though naturally greater than in August. The reinfest- 

 ation, to some extent, of petroleum-treated trees from adjacent ones is 

 shown by the much greater numbers of living scales found on the side of 

 tree 15, next to tree 14, the latter a kerosene-treated tree literally alive 

 with the young pests. Compared with kerosene, a mechanical petroleum 

 emulsion is a gratifying success. The tests with 25% emulsion do not 

 give markedly different results from those of the more dilute mixture. 

 Scales escaped on the badly and very badly infested trees treated with 

 this as well as with the other. The results are not enough better to 

 warrant the use of the higher per cent of oil. It is a source of great 

 pleasure to state that the extensive spraying of fruit trees infested by San 

 Jos6 scale on the estates of L. L. Morrell, Kinderhook (N. Y.) and of 

 W. H. Hart, Poughkeepsie (N. Y.) gave substantially the same results as 

 those above recorded. Mr Hart used an oil obtained from the Frank 

 oil co., Titusville (Pa.). The company states that the oil supplied Mr. 

 Hart ran above 43 on the Beaume oil scale. A sample sent me in Feb- 

 ruary 1901, tests 44. 9 and their oil is claimed to run from 44 to 

 45 . Both of these gentlemen did thorough work and took 

 pains to go over their trees twice, the second time with the wind 



