— 141 — 



Table IV. shows the results of the examination of July 19th. 

 Eighteen infested straws were found. All larvae had penetrated 

 to the ground. All had made the circular cut and partition below 

 it, and all but four had spun their cocoons. 



From these observations it is evident that a small proportion of 

 the insects are probably removed from the wheat fields in the 

 straw ; and consequently there is danger of the spreading of the 

 species in this way. It is probable that the species was introduced 

 into this country in straw used as packing ; and it may be further 

 distributed here in the same way. 



Note 5. Oil the Date of Pupation. — Owing to my absence from 

 Ithaca during the winter, the date at which the larvae changed to 

 pupae was not definitely ascertained. On the 23d of April I was 

 able to find in the field only pupae ; but larvae which had been 

 kept cool in the hibernating-room of the Insectary had not yet 

 changed to pupae. 



Note 6. Oil the Abu7idance of Cephus pygmaeics at Ithaca. — The 

 following observation will serve to indicate the abundance of the 

 species in this locality : 



In 1887 four examinations were made to determine the propor- 

 tion of wheat straws infested with the following results ; 



In a lot of no straws 10 were infested. 

 86 " 6 " 



" " 46 " 6 " 

 " " 34 " 4 " 



The following observations were made in 1889 : 



In one square yard containing 380 straws 30 were infested. 



i< (I <i 11 TXyO " 21 " " 



380 " 19 " 



< < < " I i < < IXyct " ? ? " " 



" " " " 360 " 15 " 



<( <i (( (4 nf^C ** T^ *' '* 



" bundle containing 2325 " 99 " " 



" " " " 2376 " 16 " 



" " " 2373 " 173 " 



The three bundles were taken from widely different parts of the 

 field. The six square yards examined were all situated on the 

 side of the field nearest the clover field from which the Saw-flies 

 spread. They therefore, doubtless indicate an unusually large 

 proportion of infested straws. At the time these six examina- 

 tions were made I was unable to remove the grain from other parts 

 of the field, on account of other experiments which were being 

 conducted upon it. 



