94 



It is thought that by some suitable process of sifting a large proportion 

 of infested flour ma}' be recovered for prompt commercial use. free 

 from mites. 



Dendy (A.) & Elkington (H. D.). Report on the Effect of Air-tight 

 Storage upon Grain Insects. Part II. — Report of the Grain Pests 

 (War) Committee of the Royal Society, London, no. 3, November 

 1918, pp. 3-14. 



Further experimental evidence is adduced in this report as to the 

 efficiency of hermetical sealing as a means of destroying insect pests 

 of grain and flour. The results of the experiments detailed are, 

 briefly as follows ; — ^Destruction by hermetical seahng of infested 

 wheat was obtained with larvae and eggs of Calandra oryzae at 75° to 

 80° F. in 28 days, with larvae and eggs of C. granaria at the same 

 temperature and period, with larvae and pupae of C. oryzae at 88° F. 

 in 25 days. It was found that the early stages of C. oryzae are 

 apparently a good deal more susceptible to the effects of hermetical 

 sealing than the adults. An apparently clean sample of Indian 

 wheat, kept for a few months at a warm temperature in a moist 

 atmosphere, became badly infested with Rhizoperlha dominica, but 

 after hermetical sealing for 23 days at 88° F. the grain was found 

 to be insect-free and after keeping at room temperature for nine 

 weeks still showed no living insects. This beetle was entirely destroyed 

 by hermetical sealing for 3 days at 88° F. in a small air-space. Larvae 

 of Trogoderma khapra were destroyed in a small air-space by hermetical 

 sealing for 6 days at 88° F., but the indications are that in a large air- 

 space this species would be considerably less affected than Calandra 

 spp. Further experiments in this connection are desirable. The 

 destruction of all insects was obtained by hermetically sealing wheat 

 infested with Triholium castaneum for 2 days at 88° F. ; Laemophloeus 

 sp. was destroyed in 3 days at 88° F., Silvanus surinamensis in 2 days, 

 adults of Gnathocerus corniitus in 5 days, larvae of the same species in 

 3 days, and larvae of Epheslia kuhniella in 5 days, all at 88°F. Flour 

 heavily infested with larvae of E. kuhniella was cleared of infestation 

 by sealing for 7 days at 84° to 87° F. Mites occurring abundantly 

 in wheat were destroyed by sealing for 24 hours at 75° to 80° F., and 

 again, in a large air space, in 19| hours at 88° F. The mite in this 

 case was probably Tyroglyphus siro. 



In the light of these experiments, it is considered probable that air- 

 tight storage is the best method of preserving grain and cereal products 

 from the attacks of insects or mites, and the same method would 

 also apply to rats and mice. The authors refer to the apparent 

 failure of this method as applied to army biscuits [see this Rerieiv, 

 Ser. A, i, p. 292] and express doubt as to whether in really hermetically 

 sealed tins any serious damage from Ephestia kiihniella and other 

 insects could arise. It is suggested that the army authorities should 

 investigate further with a view to determining how far damage can 

 occur in really air-tight tins in which the air-space is kept as small 

 as possible. It is recognised that an experiment with weevil-infested 

 wheat on a large scale is desirable, and it is hoped to carry out such 

 an experiment in the near future. 



