1899] WIREWORMS. 69 



and Rape-cake on Wireworms, was kindly placed by him in my bands, 

 with the remark (Nov. 14th, 1898): — "I have been trying if Cotton- 

 oil cake (very deadly to mammals) would kill Wireworms. The 

 experiment is a very rough one. Enclosed is a description of what 

 happened." — (B. D.) 



'^Description of experiments on Wireworms, — One hundred worms 

 were placed in each of three jars of earth, and fed respectively with 

 Castor-oil seed cake, with Rape-cake, and with nothing. The cake 

 was given in great abundance in both cases, being applied as fast as 

 the worms seemed to dispose of it — that is to say, as fast as it dis- 

 appeared, though the disappearance may not have been entirely due 

 to its consumption as food, but partially to decomposition. 



" By the end of two months about a third of an ounce of cake had 

 been supplied to each jar. The soil in each case only weighed about 

 ten ounces, and the cake applied must have been at the rate of far 

 more than one hundred tons per acre ; so that the experiment, even if 

 an exaggerated one, seemed well calculated to show whether there 

 might be any specific difference in the effects of the food supplied. 

 The earth was of course kept equally moist in all three cases. 



" At the end of three months the pots were turned out, and it was 

 found that, of the hundred worms which had had no food at all in 

 addition to the earth in which they lived, ninety-eight were alive, 

 though their condition was very meagre ; of the hundred worms 

 supplied with castor-oil seed cake, ninety-three were alive and in good 

 condition ; of the hundred, however, that had been fed upon ground 

 Rape-cake, only six were alive. 



" It would appear, therefore, that Rape-cake, when supplied in 

 such superabundance as in this experiment, brought about a large 

 destruction of the worms, though it does not by any means necessarily 

 follow that it would do so when used on the small scale adopted in 

 actual farming. On the other hand, it seems to be abundantly clear 

 that Castor-oil seed cake, although it is virulently poisonous to higher 

 animals, fails to exercise any poisonous effect upon Wireworms, which 

 are apparently indifferent to its acrid poison. 



" Still more cake was given, but this cake, the weather being 

 warmer, decomposed, and the soil became infested with smaller life, 

 which seems to have brought about conditions uncongenial to the 

 Wireworms ; and it may be also that the effects of crowding for so 

 long a time without change of soil were bad for them ; for first the 

 cake-fed ones died, and then those without food." — (B. D.) 



The foregoing observations need no comment beyond Dr. Dyer's 

 own remarks as to the presumable cause of the ultimate death of the 

 Wireworms after the period of three months had expired, of which 

 notes are given. But two of the special points recorded well deserve 



