HOUSEHOLD INSECTS 243 



little animals are not insects at all, for they are possessed 

 of eight legs, instead of the six with which all true insects 

 are provided. Despite their minuteness, they have been 

 known from very early times, and, by Aristotle, they were 

 considered to be the smallest of living creatures. Their 

 small size, varied diet they can live upon ham, flour, and 

 other stored goods, as readily as upon cheese, coupled 

 with a fecundity that is almost incredible, has resulted in 

 their attaining an almost world-wide distribution. The 

 two species are often to be found feeding together ; both 

 are almost colourless, but Tyroglyphus longior is the larger 

 of the two and has longer hairs projecting from its more 

 elongated and cylindrical body ; it is also less lethargic in 

 its movements. The life-history of the cheese mite is 

 curious and interesting. One stage, the hypopus, is so 

 unlike the parent mite that, for a long time, it was con- 

 sidered to belong to another genus ; in fact, it was not till 

 1868 that Claparide showed that the hypopus was really 

 a stage in the development of the Tyroglyphids. 



Every housewife knows how a cheese, once attacked by 

 a few mites, quickly becomes a crawling mass and is finally 

 reduced to the state of a powder, composed of mites, to- 

 gether with their excrement and cast-off skins an appetis- 

 ing morsel for the most fastidious palate ! This rapid 

 increase in the cheese mite community is specially notice- 

 able in the warm summer months, and is partly accounted 

 for by the fact that the females are viviparous they 

 produce living young, and so, by eliminating the egg stage, 

 there is a considerable saving of time. The young are 

 soon full-grown, and at once proceed to their main business 

 of life, the multiplication of their kind. 



The most interesting question in the life -history of a 

 cheese mite is, What becomes of the mites when all the 

 cheese is eaten ? A study of the mites during the summer 

 months will not be much help. Their powers of locomotion 

 are feeble, and their bodies are soft and easily damaged, so 



