154 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



NOTES ON INSECTICIDES. 



By A. F. Burgess, Culumhus, Ohio. 

 [Withdrawn for ]iublicatioii elsewhere.] 



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

 grain infested with the larva^ of FJodia inter punctella Hbn. The 

 silk spun by the larva^ formed a dense coating on the outsidt> 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 larvse, although those on the outside 

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

 bags. 



Mr. Washburn asked if there were 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 rai)idly. 



Mr. Quaintance said that experiments had shown that ])enetration 

 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 wnth the lime-sulphur- 

 salt wash by the Bureau of Entomology. Twenty-three or 24 formu- 

 las were tested during 1005 in western New York, in Maryland, and 

 in Georgia, the work thus being extended over a considerable range 

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

 Quaintance further stated that washes ccmtaining less than 15 pounds 

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

 destroying the scale, and best results Avere 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 suljjhur with the lime after 

 the water has been added to tlie latter, and while it is in the i)rocess 

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

 the latter is l)eing 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 *■' 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- 



