2oo entomological news. [October, 



DEPARTMENT OF EGONOMIG ENTOMOLOGY. 



Edited by Prof. JOHN B. SMITH, ScD., New Brunswick, N. J. 



Papers for this department are solicited. They should be sent to the editor, Prof. John 

 B. Smith, Sc.D., New Brunswick, N.J. 



Crude Petroleum as an Insecticide.— The use of kerosene against insects 

 naturally turned attention to other oils of the same class and to different 

 grades of the same oil. Experiments were made, therefore, with a num- 

 ber of them which have never been recorded, and as they all resulted in 

 failures, probably never will be. The use of the crude petroleum was 

 suggested to me by Mr. Lafayette T. Schanck, one of our Monmouth 

 County fruit-growers, because he had employed it for many years in de- 

 stroying lice on stock and for various garden insects. He claimed that it 

 was as good an insecticide as kerosene and much less violent in its action 

 on the subject, while kerosene would remove the hair from most of the 

 animals to which it was applied, crude oil never did, but gave a better and 

 cleaner coat, inducing a new and vigorous growth of hair on bare patches. 

 His experiments on vegetation were too indefinite to quote, but there was 

 enough in it to make me determine to try it if possible. In January I 

 induced a grower to risk a row of dwarf pears, very badly infested with 

 San Jose scale for dangerous experiments, and one of these trees was 

 painted from the base to the tip of the twigs with crude petroleum. The 

 application was as thorough as it could be made with a brush and the tree 

 turned a dark chestnut-brown at once. A few days afterward an exami- 

 nation on a bright sunny day showed the surface studded with drops of 

 water that had condensed on it. Everything was penetrated by the oil 

 and the tree was considered as hopelessly injured. The scales were simply 

 soaked and great patches could be lifted up and removed without effort. 

 In due season, however, this tree as well as those surrounding it showed 

 the swelling leaf buds, and the foliage, as it developed, was even better 

 and richer in color. Fruit buds were also developing normally, and there 

 was nothing in the appearance of the tree to indicate that anything that 

 could be considered an heroic application had been made. The twigs 

 and all the wood, however, retained the oily appearance, on which a coat- 

 ing of dust was now forming, so that the tree looked almost black. Fruit 

 set normally and a fair crop; a little less perhaps than on some other trees, 

 and there were a few dead spurs on the tree; but as this was one of the 

 scaliest trees in the orchard, and as others, no worse, died in part or en- 

 tirely, although untreated, it would be unsafe to charge this to the petro- 

 leum. It was anticipated that the August sun would drive the oil into the 

 tree and kill it, but even this was not the case, and up to the date of 

 writing this tree is one of the most vigorous in the orchard, while the 

 fruit is ripening normally, the pears — Duchesse — as perfect as any of their 

 kind. The tree has made a better growth, with longer shoots, than any 



