344 Forty-fourth Report on the State Museum 



arsenities are more liable to injure the foliage when it is more 

 advanced than when it first puts forth. If this shall be established, 

 later sprayings should be of reduced strength. 



The different fruit trees show different degrees of susceptibility to 

 the poisons. It appears that the apple and cherry are the least 

 affected, the plum is more susceptible, and the peach the most readily 

 injured. For plum trees one pound of the arsenite to 250 or 300 

 gallons of water should be used, while for the peach, a dilution to at 

 least 300 gallons [for Paris green, and 400 gallons for London 

 purple] is recommended. It is probable that further experiments 

 will show that while Paris green is preferable for use on one or more 

 of the fruit trees, London purple is less harmful to others, and the 

 reverse. 



Different results with reference to injury to foliage have been 

 obtained through spraying at different hours of the day, and under 

 different atmospheric conditions. 



Although there has been some conflicting testimony, it would seem 

 that white arsenic may not be used with safety, and certainly not 

 when it has been dissolved by boiling or otherwise. 



Spraying with Water. 



With merely mentioning, in passing, other principal insecticidal 

 liquids that are employed in spraying, such as kerosene emulsions, 

 alkaline solutions, pyrethrum water, tobacco water — each of which 

 has certain adaptation to certain insect attacks, I will ask your atten- 

 tion to a method that has been brought to our notice within the past 

 year as having proved efficient in arresting the injuries of one of the 

 chief pests of rose-growers — the rose-slug, Monostegia rosce (Harris). 

 We are indebted for it to Mr. L. O. Howard, first assistant of the 

 entomological division at Washington. I quote a communication 

 recently made by him to Orchard and Garden. 



I enjoyed fighting the rose-slugs in my garden last summer, par- 

 ticularly as they were so easy to kill. It was an old garden with many 

 varieties of roses. During the early summer there was abundant rain 

 and I did not bother myself one way or the other about the plants, as 

 they bloomed plentifully and looked green. But when a dry spell came, 

 the leaves turned brown at once, and an examination showed them to 

 be covered with slugs of all stages of growth. I sprayed them with 

 a tobacco-soap solution which killed them at once, but stained all the 

 petals brown at the tips. I puffed on pyrethrum mixed with spoiled 

 flour, which also killed them, but pyrethrum is rather expensive. I 

 dusted them with sifted coal ashes, which also killed them, but it 

 made the bushes look nasty. As the drought continued I brought 

 out my hose, and discovered, to my delight, that a strong stream of 

 water directed on the foliage each evening was the most efficacious 

 and the neatest remedy that I had yet found. During the remainder 



