LIFE IN THE HOUSE 13 



The insects of the house may be either slightly or closely 

 connected with it. Some are mere casual visitors, which, 

 like wasps or humble-bees, enter through a door or a 

 window, and find themselves caught in a trap. They may 

 escape after a time, or exhaust their strength in vain 

 efforts to fly through the window-pane. These casuals 

 enter the house by mistake, and many enter it only to 

 starve. Next may be mentioned the insects which are 

 parasitic on man. Some of these make use of the house 

 as a shelter and breeding-place, but there are others which 

 belong rather to the inhabitant than to 'the house, and 

 multiply just as freely out of doors, as for instance in 

 camps, or among armies which bivouac in the field. A 

 third class consists of insects which are bred out of doors, 

 but regularly enter the dwelling for shelter and food ; the 

 house-flies are the best example. Lastly we come to the 

 insects which better than any others deserve to be called 

 insects of the house. They are born and bred in the house, 

 and obtain all their food from it. To this class belong 

 cockroaches, crickets, furniture-beetles, clothes-moths and 

 silver fishes, besides others which are less easily remarked. 



House-spiders of more than one kind have made them- 

 selves quite at home in our dwellings. Mites attach them- 

 selves rather to the food of man than to his houses. One 

 true crustacean, the wood-louse, which frequents out- 

 houses and gardens, now and then establishes itself in a 

 cellar. 



No green plants can permanently maintain themselves 

 in the darkness of an ordinary dwelling, but moulds and 

 bacteria often find the conditions favourable, and multiply 

 so greatly as to affect the health and prosperity of the 

 owners. Most of them are injurious, but a few have 

 their uses in the preparation of food, and thousands of 

 years ago, long before their real nature was suspected, 

 were enlisted in the service of man. Of these last some 

 account will be found in a later chapter (p. 50). 



