34 Life History and Economy of the Cheese Mites 



the bell jar. The bi-sulphide was then left to evaporate. The reason 

 for elevating the fumigant is that the vapour is heavy and therefore 

 sinks. The majority of the mites were killed, but some still survived 

 at the base of the cheese. (2) The cheese was sprayed with the bi- 

 sulphide by means of an ordinary garden spray. It was then inverted 

 and the base treated. This method is, however, wasteful. (3) The 

 cheese was painted all over the surface with the bi-sulphide by means 

 of a large paint brush. This method was found to be the most effective, 

 though it would be difficult of application on a large scale and the cost 

 might be prohibitive^. 



It was necessary to treat the cheeses three times, once to kill the 

 adults, a second, at an interval long enough to allow for the hatching 

 of the eggs, to kill the larvae, and a third after a similar interval to 

 make sure that all were killed. Thus the four cheeses received their 

 first treatment on September 11th, 1916, the second twelve days later, 

 and the third after the same interval. No mites were afterwards 

 observed, the cheeses ripened satisfactorily and were kept free from 

 mites from October, 1916, to February, 1917, when they were returned 

 to the dairy and sold. 



Further experiments with Carbon bi-sulphide will be carried out on a 

 larger scale during the present year. I do not think, however, that it 

 would be easy to free large numbers of Stiltons from mites by any fumigant 

 when once they have been attacked. The mites are so small and breed 

 so rapidly that it is extremely difficult to exterminate them. The 

 hope seems to lie rather in preventive methods, that is, in a thorough 

 cleansing of the dairy in the interval between the clearing out of the 

 ripe Stiltons and the making of the new ones, and an attempt to do this 

 will be made in the cheese room at University College, Reading. 



The following recommendations arise naturally from what has been 

 said above : 



(1) All the windows should be netted to prevent the entrance of 

 flies and moths, which carry mites. If doors are left open, they should 

 have a netted inner door for the same purpose. This precaution 

 would also eliminate "skippers" from the cheeses, by preventing the 

 ingress of cheese flies. 



1 The price of Carbon bi-sulphide is at present \\d. per lb. About 5 — 8 ozs. were 

 used for the four cheeses in question at each fumigation and there were three such fumi- 

 gations, so that the total cost was about \s. M. for the four cheeses. The cheeses were 

 subsequently turned but not brushed as there was no dust on tliem. The cost of brushing 

 was therefore saved. 



