— 142 — 



Note 7. On the Effect of the Boring of Cephtis pyg?naeus upon 

 the Quantity of Grain Developed. — In 1887 only a single observa- 

 tion was made. It was found that ten infested stalks produced 

 273 kernals which weighed 10 grams ; while ten stalks not infest- 

 ed produced 261 kernels which weighed a little more than 1 1 

 grams. This indicates that the kernels from the infested stalks 

 were not so well filled as those from the non- infested stalks ; for 

 although there were a greater number of the former, they did not 

 weigh as much as the latter. In fact the average weight of the 

 kernals from the infested stalks was 13 per cent less than those 

 from the other lot. 



In 1889, unfortunately, a comparison was not made in the 

 weight of the kernels from infested and non-infested stalks. The 

 importance of this was not appreciated till I undertook to digest 

 the results of the experiments. Comparisons were made between 

 the weight of the grain from the infested straws in each bundle, 

 and the weight of the grain from three lots of non-infested straws 

 from the same bundle. The following are the results obtained. 

 A possible explanation of these results has been suggested on 

 page 132. 



In bundle No. i : 



The grain from 99 infested heads weighed 85 grams. 



" " 99 non-infested heads weighed 70 grams. 



" " 99 " " " 77 " 



" " 99 " " " 67 " 



In bundle No. 2 : 



The grain from 16 infested heads weighed 12.3 grams. 



" " 16 non-infested heads weighed 11.3 grams. 

 16 " " " 13.6* " 



16 " " " II. 9 



In bundle No. 3 : 



The grain from 173 infested heads weighed 165 grams. 



" " 173 non-infested heads weighed 140 grams. 



173 " " " 130 " 



173 " " " 120 " 



Note 8 : Parasites of Cephus pygmaeus. — On the 23d of April 

 a crippled Ichneumon-fly was found emerging from a cocoon 

 of Cephus pygmaeus. Unfortunately, the specimen is in too poor 

 a condition to admit of determining the species. 



On the 20th of July a parasitic larva was found in the cell of a 

 Cephus larva at the base of a wheat stalk. The parasite was 

 outside of the body of the Cephus. The latter was soon destroyed ; 

 and the parasite spun a cocoon, from which it has not yet emerged. 



* This lot was composed of large, selected heads. 



