32 Life History and Economy of the Cheese Mites 



(1) That the mites could be carried by flies, which were observed 

 crawling over the cheeses. 



(2) That the mites, being so small, could be blown by a draught 

 across the small space between shelves and trestle. 



(3) That the person who turned the cheeses, in spite of the care 

 taken, may have carried the mites. 



A fly paper was hung up in the room and the flies caught on it were 

 examined under the microscope. Mites in small numbers were found 

 attached to their legs, so that there seems to be no doubt that mites 

 can be carried in this way. In fact, the Hypopus stage (see life history 

 above) is specially adapted for conveyance by this means. If the mites 

 can be carried short distances by flies, there is every possibility that 

 new cheese rooms become infested by mites carried by flies, moths 

 and other insects which have previously visited places where these small 

 creatures abound. 



Experiment 2. The trestle in this case was not grease banded, but 

 on it was placed a large bath containing water to a depth of about 

 two inches. It had been previously ascertained that mites could not 

 traverse a piece of water, so that any mites that crawled up the legs 

 of the trestle and over the edge of the bath would fail to reach the 

 cheeses, which were placed on boards elevated above the water. 

 These cheeses were attacked by raites at about the same time as those 

 in Experiment 1, that is to say, about two weeks later than those 

 that were put on the shelves, and presumably from the same causes, 

 for moths and flies were seen on these cheeses also. 



Of the three possibilities mentioned above, therefore, the first 

 becomes a fact, viz., that flies and moths can carry the mites. No 

 experiment has yet been made to show wdiether the mites can be blown 

 through the air, though it is highly probable that this is the case, at 

 any rate for short distances. The possibility of the person who turned 

 the cheeses conveying mites must not be overlooked, though every 

 care was taken to prevent it. Anyone who has turned mite-eaten 

 cheeses, however, will realise that human beings can carry mites from 

 one place to another, and will have experienced the tingling and itching 

 sensation due to the presence of the mites on the skin. Although 

 mites have no eyes^, they can distinguish between light and darkness, 

 and of the two they prefer darkness. If the breeding cells mentioned 

 above were kept in the light, the mites hid under the blotting paper 



^ Carpoqliiphufi has "eyp-Hke organs," Init these have no pigment nnd it is doubtful 

 if this mite can see. 



