74 



increase of mites, especially if associated with mouldiness ; indeed mould and mites most 

 frequently go together. 



The Commom Cheese Mite {Tyroglyphus siro). 



• 



This tiny creature, scarcely visible to the unaided eye, is soft, smooth and fleshy, with 

 a whitish body, and feet furnished with suckers and claws. Fig. 63, which represents one 

 of these mites highly magnified, will convey a better idea of its 

 general aspect than any verbal description we can give. It lives in 

 almost every kind of cheese when a little decayed, and particularly 

 in the harder portions. When in a warm atmosphere they are 

 active, constantly gnawing at the cheese and reducing it to powder. 

 This powder is composed of little greyish balls of excrementitious 

 matter, eggs, both empty and unhatched, larvae, pupae, and perfect 

 mites, with cast skins and fragments of cheese; Exposed to a low 

 temperature, the individuals soon gather into groups or heaps in 

 hollow places in the cheese, and there remain in a state of torpidity 

 until awakened again by warmth. This mite is also found in flour. 



It multiplies very rapidly either in cheese or flour. A few 

 specimens transferred from a mitey cheese to an old cheese not mitey, 

 will soon colonize it thoroughly. They are probably harmless, since Fig. 63. 



there are no records of any disease occasioned by them, although they are daily eaten in 

 numbers too great to be estimated, and so carelessly, that hundreds of living individuals 

 must escape the grinding of the molars and be swallowed alive. 



The Scarcer Cheese Mits {Tyroglypus longior). 



This species is found associated with the common cheese mite, but seldom in any great 

 abundance, rarely in larger proportion than fifteen or twenty, and sometimes not more 

 than one, to a hundred. It is very easily distinguished from the common cheese mite, by 

 its larger size, greater length of body, and longer hairs, while very similar in its habits it 

 is much quicker in its movements. This species also attacks the dried Spanish flies or 

 cantharides kept by druggists, and used for blistering purposes. A French naturalist, M. 

 M. Fumouse, has studied the life-history of this mite, by placing some of them with a 

 sufficient supply of food between two plates of glass. The females laid oval eggs in great 

 abundance, which hatched in from ten to fifteen days, the young mites being at first as 

 usual six-footed. During their growth, and after casting their skins once or twice, they 

 acquire an additional pair of legs, making eight in all, and soon reach maturity. 



This species some fifty years ago acquired much notoriety on account of its having 

 been stated that it could be produced by electricity. At that time the idea obtained in 

 the minds of some that electricity was the source of many of the phenomena of life. Two 

 experimenters, Messrs. Cross and Weekes, of England, endeavoured to ascertain whether 

 organic beings could not be produced by electricity. For this purpose pumice stone kept 

 moist by a dilute solution of silicate of potash and muriatic acid was subjected to a con- 

 stant stream of electricity, and after a time some of these mites were found wandering 

 about the apparatus, and the conclusion was at once arrived at that they had been pro- 

 duced through the agency of electricity. A specimen was sent to a French naturalist 

 who had made a special study of mites, who found it to be a female of this species with 

 its body distended with eggs, which, as he drily remarked, seemed rather an unnecessary 

 complication in a new creation. 



Tyroglyphus Malus 



(fig. 64), is a North American mite, which is a friend to the fruit grower since it destroys 

 the eggs of the oyster-shell bark louse, so iniurious to the twigs of the apple tree. 



