ENTOMOLOGY 397 



ness, which should be a warning to the operator that it is time to 

 seek fresh, pure air. 



Sulphur Dioxid. The fumes of burning sulphur, namely, sul- 

 phur dioxid, with some sulphur trioxid, have long been one of the 

 standard insecticide gases for the destruction of insect pests in rooms 

 or dwellings, and notably for the bedbug (Cimex lectularius L.). 

 Doctor 'Stiles, of the Public Health and Marine-Hospital Service, 

 reports very successful fumigation and disinfection of frame cot- 

 tages at a seaside resort for bedbug infestation by burning sulphur at 

 the rate of 2 pounds of stick sulphur for each 1,000 cubic feet of 

 space. Sulphur candles for such fumigation are a standard supply 

 material to be purchased anywhere. Sulphur fumes are also em- 

 ployed for disinfection from disease germs, and also in the more 

 recent yellow-fever work for the destruction of mosquitoes in dwell- 

 ings. The chief objection to the sulphur fumigation arises from 

 the strong bleaching action of the fumes in the presence of moisture 

 and their powerful destructive action on vegetation. 



For the disinfection of ships and ships' cargoes, particularly of 

 grain, sulphur dioxid, under the name of Clayton gas, is now being 

 extensively employed. These experiments showed that sulphur 

 dioxid, under pressure such as can be maintained in an air-tight 

 compartment or in the hold of a ship, has great penetrating power 

 and is very efficient as a means of destroying all kinds of insects. 

 The germinating power of seeds is quickly destroyed, but no injury 

 results to the feeding or cooking quality of cereals. It can not be 

 employed in the case of living plants, nor with moist fruits or pro- 

 ducts, such as apples or bananas. The best results in the case of 

 insects infesting grain and seed, such as Calandra and Bruchus, 

 which are often inclosed in the seeds, were obtained by the use of a 

 low percentage (1 to 5 per cent of gas) for a period of twelve to 

 twenty-four hours. ' Employed in this way the gas is a very effec- 

 tive means of disinfecting stored grain or similar products not in- 

 tended for planting, and has the additional advantage of entirely 

 eliminating the danger of explosion and fire. (F. B. N. Y. Dept. 

 of Agr.). 



HEAT METHOD OF CONTROL. 



The treatment by heat, while new in its application to entire 

 buildings, has during the past two years been used very successfully, 

 both in the control of the Indian-meal moth and in that of the 

 related Mediterranean flour moth. It is, of course, only applicable 

 to mills heated by steam. In the proper application of this method 

 the mill should be thoroughly piped and furnished with suitable 

 radiators. Sufficient radiator surface should be supplied to obtain 

 a temperature of 120 to 125 F. A few courses of 11/4 -inch pipe 

 placed along the side walls should easily bring about the desired 

 results. If a warm day in the summer is selected and the steam is 

 employed at a pressure of 75 tp 100 pounds, only a small amount of 

 radiator surface is needed. To permit the most effective penetration 

 of the heat, the bags of nuts should be piled only a few feet deep, as 

 experience has shown that some time is required for the peanuts 



