222 



were the worst sufferers, as the millers and dealers, by means of rapid 

 handling, disposed of their products before the eggs could develop. 

 Housekeepers were therefore advised to heat all their substitutes as 

 soon as they were brought into the home, in order to kill any eggs or 

 larvae that might be present. It was found that when the cereal 

 was less than two inches deep in pans and was heated slowly until 

 the surface temperature reached 85° C. (185° F.), the source of heat 

 could then be turned ofE and in the course of half an hour the heat 

 would diffuse until all parts of the cereal had passed well above the 

 temperature fatal to insects. If the temperature is allowed to rise 

 above 90° C. (194° F.) the cereal will be injured. A mixture of 

 carnauba wax and paraffin has been devised which serves an an indi- 

 cator [see this Review, Ser. A, vi, p. 434]. Cleanliness in handling 

 the flour has undoubtedly reduced infestation, while the exchange 

 or refilling of used sacks has been the source of much trouble. If 

 empty sacks be placed in an oven, three or four deep on boards, and 

 left for five minutes, all insects are killed at the usual temperature 

 of 232° C. By heating all utensils in the oven infested bakeries 

 have been entirely freed from insects. 



A study has been made of the relative susceptibility of various 

 flours and cereals ; the relations of Triholium confusum to five grades 

 of wheat flour and various wheat flour substitutes being investigated. 

 The results showed no percentages of infestation constant enough to 

 denote decided choice, so long as the coarseness remained about 

 equal in all cereals ; but when bran from rye meal was introduced a 

 decided preference for this medium was shown. The element of 

 flakiness was found to be the dominant factor in choice, rather than 

 nutritive differences. In the case of both bran and sawdust, a far 

 higher percentage of beetles chose the coarse rather than the finely 

 ground variety of the same material. 



In the study of tlie relative development of the insects in the various 

 wheat flours and substitutes it was found that the larval life might 

 be prolonged in certain wheat flour substitutes and that this prolonga- 

 tion took place in the last larval instar. In some cases the life-cycle 

 was twice as long as in others. The factor of relative development 

 must, however, await further investigation before its importance in 

 influencing susceptibility can be judged. 



Britton (W. E.) & Zappe (M. P.). Kerosene Emulsion versus Nicotine 

 Solution for Combating the Potato Aphid. — Jl. Econ. Entom., 

 Concord., N.H., xii, no. 1, February 1919, pp. 71-81. 



A heavy infestation of Macrosiphum solanifolii, Ashm. (potato 

 aphis) in Connecticut in 1917 necessitated vigorous methods of control, 

 and in early July potato fields were sprayed with Bordeaux mixture, 

 lead arsenate and Black-Leaf 40 at the rate of ^ pint to 50 gallons 

 of the mixture. The spray was not very effective as the waxy nature 

 of the Aphids caused it to roll away in drops. Experiments 

 were therefore tried with various materials to act as spreaders, 

 but nothing seemed to be a successful substitute for soap, which 

 is considered likely to cause injury when used in the combination 

 mixture. The demand for nicotine sulphate became so great that 

 supplies were used up, and kerosene emulsion was then tried against 



