ENTOMOLOGICAL SOCIETY OF ONTARIO. 75 



stronger nature, which would injure the foliage but will do no harm to the trees 

 during the winter, when they are in a dormant condition, and yet will have the 

 effect of destroying the scale insect. Of the summer washes, the ordinary kerosene 

 emulsion (Riley-Hubbard formula) and a resin wash [resin 20 lbs., caustic soda (70 per 

 cent, strength) 5 lbs., fish oil 3 pints, water 100 gallons] were recommended by Mr. 

 Howard, and used with success during the past summer. On peach trees, owing to the 

 susceptibility of the foliage to injury, the stock kerosene emulsion was diluted with fifteen 

 times its volume of water, instead of nine times, the usual strength advised for most other 

 plants. It was found advisable to repeat the sprayings at intervals of about a week. 

 The young scale insects were noticed on May 19th at Riverside, Md., and the females, 

 viviparous in habit, gave birth to young for a full month. This was upon peach trees, 

 and it was found that the resin wash killed the scales more quickly than the very diluted 

 kerosene emulsion, and, as Mr. Howard points out, this rapidity of the work is impor- 

 tant, since where a full-grown female is sprayed with kerosene emulsion, she may live 

 for three or four days, during which time she brings forth young ; whereas if sprayed 

 with the resin wash, fewer young scales are produced. The resin wash, however, is 

 readily carried off by the rains, while the kerosene is more resistant. 



In Professor J. B, Smith's investigations in Pennsylvania, it is recorded (Insect 

 Life, VII, p. 159) that, "he has visited the locality at Atglen, Pa., and found that in an 

 orchard of over 7,000 trees, all of certain varieties, and a few of others, were infested by 

 the scale. As a result of his recommendations, kerosene emulsion has been applied three 

 times to most of the trees at intervals of ten days, up to the first week in June, The 

 treatment has been absoluteb" successful." 



For lointer washes the kerosene emulsion and resin washes may be made stronger. 

 The stock kerosene emulsion has been used diluted with only four and a half parts of 

 water, and tor the resin wash the same ingredients were used in the following propor- 

 tions : Resin, 30 Bbs. ; caustic soda, 9 lbs. ; fish oil, 4| pints ; water, 100 gallons. 



" The most favored winter remedy in California, however, is the lime, salt, and 

 sulphur mixture. This consists of unslaked lime, 10 lbs. ; sulphur, 5 lbs. ; sto-ik salt, 5 

 lbs. ; water to make 15 gallons. This wash will do great damage to the trees if applied 

 during the growing season, and should be used only In winter. All the sulphur and half 

 the lime are placed iu a kettle and 8.\ gallons of water added, after which the contents 

 of the kettle are boiled briskly for about an hour. The solution which at first is yellow 

 from the sulphur, will turn very dark brown, assuming more or less of a reddish tint, 

 and will finally change from a thick batter to a thoroughly liquid condition, the product 

 being ordinary sulphide of lime. All the salt is added to the remaining 5 pounds of 

 lime and the latter slaked, after which the slaked lime and salt are added to the sulphide 

 of lime already obtained, the whole being then diluted with water to make 15 gallons. 

 This should be strained before application, as it does not form a perfect liquid solution 

 on account of the considerable quantity of undissolved lime, which will soon sink to the 

 bottom unless the solution is constantly stirred while being sprayed." 



The third method of fighting scale insects is known as the Gas Treatment. This 

 has been extensively used in California but is an expensive operation, and the materials 

 necessary are very poisonous and dangerous to have about. It consists, briefly, of cover- 

 ing the tree to be treated with an air-tight tent and then filling the tent with the poison- 

 ous fumes of hydrocyanic acid gas, which is generated by placing 1 oz. of cyanide of 

 potassium, I fluid oz. of sulphuric acid, and 3 fluid oz. of water in an earthenware vessel 

 beneath the tent. The gas is very light and rises to the top of the tent, and if this be 

 kept on the tree for half an hour, every scale will be destroyed. The quantity of ingre- 

 dients given above is sufficient for a tent enclosing 150 cubic feet. 



What is wanted, however, is to know Uie best remedy, and it is satisfactory to learn 

 that on the whole the standard remedy for scale insects, kerosene emulsion, is the best. 

 In summing up his experience of the year, Mr. Howard says as follows : " Remedial 

 work against this insect is onerous, but our experience has shown that three sprayings 

 at intervals of ten days during the latter part of May and June, will practically destroy 



