154 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



NOTES ON INSECTICIDES. 



By A. F. Burgess, Columbus, Ohio. 

 [Withdrawn for publication elsewhere.] 



Mr. Britton said that he had used hydrocyanic-acid gas for bags of 

 grain infested with the larvae of Plodia inter punctella Hbn. The 

 silk spun by the larva? formed a dense coating on the outside of the 

 bags. One ounce of cyanide to 100 cubic feet was used, but after 

 thirty-six hours the gas had failed to penetrate to the interior of the 

 bags sufficiently to kill the Plodia larvae, although those on the outside 

 v^ere all destroyed. Some live Tenebrio larvae were also found in the 

 bags. 



Mr. Washburn asked if there v T ere any data on the use of sulphur 

 dioxide in flour mills. 



Mr. Marlatt replied that he had not had any experience in actual 

 mill work, but had tested it with sacks of flour and that it penetrated 

 these rapidly. 



Mr. Quaintance said that experiments had shown that penetration 

 of hydrocyanic-acid gas into the soil is so slow that it is entirely 

 impracticable to use it for soil fumigation in greenhouses. He also 

 referred to a series of experiments in progress with the lime-sulphur- 

 salt w^ash by the Bureau of Entomology. Twenty-three or 24 formu- 

 las w T ere tested during 1905 in western New York, in Maryland, and 

 in Georgia, the w 7 ork thus being extended over a considerable range 

 and likely to bring out differences due to climatic conditions. Mr. 

 Quaintance further stated that washes containing less than 15 pounds 

 of sulphur to 50 gallons of water in all cases proved inefficient in 

 destroying the scale, and best results were secured from the use of 

 washes containing considerably more sulphur, as 20 or 25 pounds to 

 50 gallons of wash. 



Mr. Smith said that his experience in Georgia showed that instead 

 of the ordinary method of mixing the sulphur with the lime after 

 the water has been added to the latter, and while it is in the process 

 of slaking, it is better to mix the sulphur with the water first while 

 the latter is being heated by steam and then afterwards add the lime 

 to the hot mixture. 



Mr. Mackintosh asked for an opinion as to the difference between 

 the so-called " flour of sulphur " and w ' flowers of sulphur/' He said 

 that he found difficulty in getting " flowers of sulphur " in Alabama. 

 The former is used almost exclusively by the fruit growers and 

 seems to give good results. 



Mr. Quaintance said that in portions of the South, notably in 

 Georgia, orchardists were using in the preparation of the lime- 



