41 



Coal-tar emulsion. — An emulsion of coal-tar with soap-suds, which 

 we made like that with kerosene — using, however, only one third 

 coal tar to two thirds soap-suds and diluting this with water, nine 

 parts to one, — was found to approximate the kerosene emulsion in 

 its action on both insect and plant. 



Twenty-five bugs were placed, September 6, on a grass plant, in 

 a small pot, and thoroughly wet with this coal-tar preparation. 

 In an hour and a quarter many of these bugs seemed dead. In 

 seventeen hours twelve were dead, six showed signs of life, and 

 seven were able to crawl. In twenty-four hours sixteen were dead, 

 eight were barely alive, and but one was able to crawl. 



Another experiment made the same day was less conclusive, 

 only seven of twenty-six bugs treated as above being dead in 

 twenty-two hours. 



Young oats completely soaked with this emulsion showed evi- 

 dent injury two days afterward, but continued to grow, and two 

 months later were as thrifty as those adjoining. 



This emulsion deserves further experiment, especially as our 

 trials were made with a weak dilution, — about three per cent, coal- 

 tar. It is much cheaper than the kerosene emulsion, coal-tar be- 

 ing only about five cents a gallon; but it is somewhat more 

 troublesome to handle. The making of the emulsion may be facil- 

 itated, however, by boiling tar and suds together before mixing 

 with the pump. 



Turpentine emulsion. — A single experiment was made, Septem- 

 ber 4, with an emulsion of turpentine in soap-suds, diluted with 

 water to contain three per cent, of turpentine. Twenty-five hours 

 after application, six bugs out of ten sprayed on a grass plant were 

 dead, and the four remaining alive. 



Lime-ioater. — Two experiments, one each with common lime- 

 water and with water from gas lime, were entirely without result. 

 Chinch bugs treated thoroughly with these fluids were all alive 

 twenty-four hours later. 



Gas lime. — Two experiments served to show that bugs will, if 

 necessary, travel across a narrow belt of fresh gas-lime (about 

 two inches wide) without appreciable injury, either at the time or 

 subsequently. 



Arsenic. — The reported results of a casual experiment made 

 with London purple by a farmer who supposed that the chinch 

 bug was as liable to poisoning by this substance as the potato- 

 beetle, led me to a partial test of the arsenical poisons. 



September 6, thirty-one chinch bugs, larvse and pupae, were 

 dusted with powdered arsenic in a bottle containing also some 

 grass blades, and confined there by a piece of netting over the 

 bottle's mouth. In twenty-four hours all but three were dead, 

 these being still able to crawl. 



