294 Forty-second Report on. the State Museum. [152] 



The Cheese-mite Infesting Flour. 

 The following communication was submitted to me from a cor- 

 respondent at Robin's Nest, 111. : 



A few days since a neighbor sent us a pan of wheat flour with the 

 request that we examine it. Setting the pan in a quiet place for 

 twenty-four hours, the surface presented a strange appearance — only 

 comparable to that of an ant-hill — as though each grain was being 

 separately moved. Slightly disturbing this surface and examining 

 through a common sun-glass of low power, it was found to be full of 

 very minute life. Taking a few particles from the mass upon the 

 point of a penknife, and placing within the focus of a botanical glass, 

 at least a half dozen lively little insects were to be seen. They some- 

 what resembled plant-lice in form, were white, evidently soft-bodied, 

 and were covered with hair, possessed of two antennae and six legs of 

 a reddish-brown color. An apparent nest, from which a dozen or 

 more would crawl forth, was not larger than the point of a small pin. 

 It is much to be regretted that there was not a proper microscope at 

 hand so that a more extensive examination might be made. Now, 

 what are they — name, family, genus, and history ? Where do they 

 come from, and what are they doing in thus desecrating the staff 

 of life ? 



Reply was made, substantially, that the insect was doubtless an 

 Acarus, or mite — one of the family of the Acaridce, which comprises 

 the mites properly so called. The species could not be determined 

 from the above description, but the conjecture was ventured that the 

 critical examination of specimens would show it to be, if not the 

 Tyroglyphus siro, well known in Europe as frequently infesting old 

 flour (since its identity with the Acarus farince of Linnaeus has been 

 established), then a closely allied species of that genus. 



In appearance it would probably bear a close resemblance to Tyro- 

 glyphus sacchari, or the sugar-mite, which occasionally may be found 

 swarming in raw sugars, looking like minute white specks scattered 

 throughout it. (The mature insects should have eight legs instead of 

 six, as above stated.) As an illustration of the abundance in which 

 these food-infesting mites may occur, it may be of interest to state 

 that in an examination of sugars, instituted several years ago in 

 London, England, to see to what extent the T. sacchari infested this 

 material, its presence, in a living condition, was detected in sixty-nine 

 out of seventy-two samples examined. In one sample of an inferior 

 quality, from the number actually contained in one grain's weight, the 

 computation was made that one pound of the sugar contained a 

 hundred thousand of the mites. In the flour above referred to, it is 

 probable that they were even more abundant than in the sugar. 



Perhaps no satisfactory explanation can be given of the presence in 

 such numbers of the mite in the flour, nor is it known to what extent 



