February, '19] CHAPMAN: INSECTS IN FLOURS 67 



and marketing of coarse flours in larger amounts than had ever before 

 been attempted. The large flour milling interests of Minnesota pre- 

 dicted insect trouble and later the wholesale Grocers' Association and 

 the Bakers' Association asked for help in protecting their stocks of 

 wheat flour substitutes from insects. 



In response to these requests work was carried on along two lines; 

 the first, to meet the existing emergency by devising methods of pro- 

 tection, and the second, a study of the ecological relations of insects 

 and the various flours and cereals. The relative susceptibility of dif- 

 ferent flours to insects is of prime importance in protecting them from 

 insects, and a knowledge of susceptibility should be the foundation for 

 a knowledge of protection. 



The emergency work was mainly concerned with the consumers, for 

 millers adopted measures of rapid transportation calculated to move 

 the products to consumption before the eggs, if any were present, could 

 hatch and cause damage. Circular letters issued through the office of 

 the Federal Food Administration from Minnesota urged dealers to 

 adopt the miller's plan of rapid handling and emphasized the necessity 

 for cleanness in their warehouses. 



The consumers did not benefit by the millers' and dealers' methods 

 of rapid handling except in cases where only a few days supply of sub- 

 stitutes was on hand at a time. Where it was necessary to purchase 

 larger supplies, the situation was most serious, for the rapid transpor- 

 tation often brought the eggs to the consumer all ready for hatching. 

 Housekeepers were advised to heat all their substitutes as soon as 

 they were brought into the home in order to kill any eggs or larvae 

 which might be present. A method of heating to obtain a temperature 

 fatal to insects and yet prevent the cereal from injury by overheating 

 was devised as a result of a series of experiments. The temperature 

 curves show differences in the different ovens used; but in all cases it 

 was found that when the cereal was less than two inches deep in pans, 

 and heated slowly until the surface temperature reached 85° C, the 

 source of heat could be turned off, in the case of a gas, gasoline, or 

 kerosene stove, or the oven door opened in the case of a coal or wood 

 stove, and in the course of half an hour, the heat would diffuse through- 

 out the cereal until all parts of it had passed well above the fatal tem- 

 perature for insects. 



For obtaining satisfactory results, it is essential that the cereal 

 should be less than two inches deep in the pans, that the heating be 

 done slowly with the fire as low as it will burn well in order to allow for 

 the conduction of heat throughout the cereal, and that the heating be 



