42 1 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 4 



observation. September 9, five specimens of the same parasite emerged 

 in the vial, indicating that the development from egg to adult in this 

 parasite covers a period of about nineteen days. While not conclusive, 

 it is reasonable to suppose that the bred specimens are the product of 

 eggs laid by the above mentioned female shortly before she was cap- 

 tured. This is of importance, as showing the opportunity for a num- 

 ber of generations of the parasite during the normal egg-laying period 

 of the moth. 



Aphidius nigripes Ashm. 



During the spring of 1909 there was a noticeable abundance of the 

 European grain louse (Macrosiphum granaria) on the wheat, oats, 

 barley and rye fields of the Experiment Station farm. On May 7, 

 it was noticed that Aphidiine parasites were abundant in the fields 

 and they continued so until the time of harvest. Parasitized aphides 

 were collected and parasites reared in considerable numbers. The 

 majority of them proved to be the above named species, although 

 another species identified as Aphidius roscv Haliday, a common para- 

 site of the rose aphis, was also present in considerable numbers. 



In the early spring of 1910, further observations were obtained on 

 the parasite. Specimens of Aphidius were first collected with a net 

 in the rye fields on March 21, when two specimens were taken. On 

 March 30 the parasite was much more abundant, fifty specimens being 

 taken on this date. Of this number all except three were males. No 

 aphides were discovered at this time on the rye, although some were 

 doubtless present as they later became quite numerous. Search was 

 made for parasitized aphid bodies which might have served as the over- 

 wintering cocoons of the parasites, but none were located. It is not 

 intended to imply by this that the parasites wintered as adults. The 

 contrary is very probably the case, since the only species of Aphidiinse 

 whose hibernation have been observed winter as larvae in the swollen 

 bodies of their host. The predominance of males at this time and the 

 absence of any parasitized aphides on the grain would seem to indicate 

 that the specimens collected were those of the first over-wintering 

 generation. 



Another collection of parasites was made on April 11, and all were 

 found to be males. The parasite was apparently less abundant than 

 on the earlier date. A few aphides were found on this date but none 

 showing parasitism. The latter part of March had been warm and 

 balmy, accounting for the early abundance of the parasite. This was 

 followed by much cold^ wet weather in April, making it certain that 

 many of the parasites must have perished. 



Several subsequent observations taken during April and May 

 showed that aphides were increasing in abundance and that the para- 



