460 HOUSEHOLD INSECTS 



least, to kill mill insects. From the experiments and re- 

 ports of Dean of Kansas it would seem that heat is a very 

 efficient and satisfactory agent for destroying insects 

 infesting grains in mills. There seems to be no reason why 

 it would not be efficient for killing household insects if it 

 can be made available. The temperatures necessary to 

 kill stored grain insects are not high. They range from 

 118 degrees to 125 degrees or above. It is doubtful, how- 

 ever, if it would be possible to develop even these degrees 

 of heat in most households. It might be done in hotel 

 kitchens and similar places where there are large boilers 

 and ranges. In ordinary kitchens the range might be 

 supplemented by one or two oil-stoves or a gas heater 

 and the temperature raised to the desired point. 



Felt has shown that cockroaches succumb to a heat of 120 

 degrees. A temperature of at least 120 degrees should be 

 maintained for an hour or more to give it time to penetrate 

 to the insects. In the case of mills the heat is maintained 

 several hours to allow it to penetrate all the infested parts. 



Heat is undoubtedly of great use in killing powder-post 

 beetles in furniture, and similarly infested wood. The 

 practical use of heat in killing household insects has never 

 been investigated, in this country, at least, and no definite 

 recommendations can be made. The writer would sug- 

 gest that before attempting to raise the temperature of a 

 room it should be made as tight as possible in order to 

 prevent the escape of the heat. 



REFERENCES TO ECONOMIC LITERATURE ON FUMIGATION 

 WITH GASES 



1900. LOUNSBURY, C. P. Formaldehyde. Kept. Govt. Ent. 

 Cape Good Hope for 1899, p. 17. 



