UNSOUNDNE3S OF GRAIN BY INSECTS. 143 



Johnston on the subject of a change in rotation. It has 

 been taken up by other authorities during the last few 

 years, and will yet more, we venture to say, be taken up. 

 If the discussion which will ensue does no other good 

 than directing attention to, and promoting inquiry upon, 

 all the points connected with the theory of rotation, it will 

 do great service to agriculture ; for the truth is, we are by 

 no means assured of what really constitutes a correct prin- 

 ciple in rotation, or whether which is, we fancy, much 

 more likely to be the case the phenomena attendant upon 

 the change of crops are not invariable but rather are variable, 

 being dependent upon a wide variety of circumstances tend- 

 ing to introduce a corresponding variety in practice. The 

 whole subject has, indeed, to be gone thoroughly into before 

 information can be eliminated which will be of trustworthy 

 service to farmers generally. Is this another subject, in ad- 

 dition to the many we have already indicated, which ought 

 to be taken up by one or all of our agricultural societies ? " 



DIVISION SECOND. 

 THE STORING AND PRESERVATION OF WHEAT. 



SECTION FIRST. CAUSES OF UNSOUND GRAIN INSECTS 



MOISTURE. 



20. Insects which Cause Unsoundness and which De- 

 stroy Stored Grain. The depredations which insects com- 

 mit upon the wheat crop are not confined to those in the 

 field, which have been described in last section ; but they 

 are carried out, and with remarkable vigour, in the places 

 in which it is stored. The following is an account of the 

 insect pests of stored grain : "(1) The Weevil (calandria 

 f/ranaria) is a snout beetle, about one-eighth of an inch 

 in length, with a slender body (see Fig. 1 8, in which we 

 give a diagram of the weevil, natural size, with part of the 

 head magnified), of a dull reddish brown colour, furrowed 



