ENTOMOLOGICAL SOCIETY OF ONTARIO. 85 



Remedies. 



Cutting down. — When a tree is found to be heavily infested with the San Jote 

 scale, the cheapest plan will generally be to cut it down at once and burn it, for it is 

 probable that a tree which has once been badly attacked will never recover its full 

 vigor, even although every scale is killed. 



Whale-oil Soap. — If, however, a tree is only slightly infested or there are special 

 reasons for trying to save it, it should be pruned bank as closely as it will stand and 

 then washed thoroughly two or three times with whale-oil soap (two pounds of soap to 

 one gallon of water). This is an expensive treatment, but, on the whole, it is the most 

 effective yet discovered. 



Kerosene Emulsion. — A treatment which has given equally good results, but a little 

 more trouble on account of the extra labor, is to spray the trees as soon as the leaves 

 fall in the autumn with kerosene emulsion (Kiley-Hubbard formula diluted with four 

 or five tin.< s its volume of water, and then before the buds expand in the spring apply 

 the two pounds to one gallon whale-oil soap wash. 



Dr. Howard found after many experiments that what is required for spraying pur- 

 poses is a caustic potash and fish oil soap which does not contain over twenty-five or 

 thirty per cent, of water. Mr. Marlatt of the United States Division of Entomology, 

 states that a new brand of soap known as Good's Caustic Potash Whale-oil Soap No. 3 

 is one of the best which has been put on the market. 



Pure Coal Oil. — A great deal of attention has lately been drawn to the treatment 

 of trees with pure kerosene or coal oil to free them from the San Joae scale. This matter 

 was first brought forwaid publicly by Prof. Webster thiee years ago, and pure coal oil had 

 also been used with success previous to that in 1893, by advice of Dr. J. A. Lintner, upon 

 the trunks of peach trees infested with the Peach Bark-borer (Phlceotribus Ihninaris, 

 Harris). (Cent. Exp. Farm Report, 1893, p. 216.) 



Prof. J. B. Smith, of New Jersey, has experimented extensively with kerosene and 

 claims that, when the work is done carefully and as he advises, the scale insects are 

 killed by this treatment better and more cheaply than by any others, and without injury 

 to the trees. 



My own experiments with coal oil have been too limited and irregular in results to 

 justify me in recommending this method, and Prof. Webster, when rf porting upon his 

 experiments says : " I own that for a time I hoped it was possible to use coal oil in 

 destroying the scale without injury to the trees ; but our experiments up to date indicate 

 that except on the apple and some of the more hardy of the other fruits, and in cold 

 weather, it is exceedingly dangerous to attempt its use ; and, until we have had time to 

 make further investigations, I wish to wain against its use otherwise than as above indi- 

 cated." On the other hand, Prof. Snoith and Mr. C. L. Marlatt have found that trees 

 can be sprayed even in summer when in full leaf with pure kerosene and no injury 

 result to the plant. Prof. Smith's instructions are as follows : " Spraying should be done 

 with the finest Vermorel nozzle and with force enough behind it to send out an absolutely 

 mist-like spray. Cover fully, but no more, that there may be no running down or lodg- 

 ing in forks or getting around the trunk down to the roots. The whole aim should be to 

 put on the thinnest complete film possible. Spraying should be done on a clear, dry 

 day, that evaporation of the kerosene may not be interfered with. The oil acts at once 

 on the insect, and as soon as its work is done, we want to get rid of it as fast as possible. 

 The trees should be dry when sprayed. If they are wet the oil will not penetrate, but 

 remain as a film over the moisture until it disappears." 



The details of the above treatment are given here because there has been so much 

 inquiry about it by Canadian fruitgrowers who have seen Prof. Smith's recommendation, 

 and it is doubtless advisable for those having infested trees to experiment upon a few of 

 them and if gcod results are obtained many valuable trees may be saved. 



Gas Treatment. — For thorough work in treating infested trees, the fumigation with 

 hydrocyanic acid gas seems in California to have given the best satisfaction. This 



