58 MASS. EXPERIMENT STATION BULLETIN 189. 



For this reason these records are not included among the hst of P. mihilalis 

 parasites. 



Only a small per cent of P. nuhilalis larvse were parasitized. During 

 the entire season of 1918 a total of about twenty individual dipterous 

 (Tachinid) parasites were bred, although several hundred larvse were 

 imder observation in life-history cages and in the process of securing other 

 biological data. The highest percentage of parasitism recorded was from 

 a collection of 50 full-grown P. nubilalis larvse dissected from the stalks 

 in a badly infested field in Revere, Mass., on Aug. 23, 1918. Two para- 

 sitic larvse emerged from the total of 50 P. nubilalis larvse, a percentage of 

 parasitism of 4. 



A fact worthy of recording here is that during July, 1918, the larvse of 

 Papaipema nitela Gn. were very highly parasitized by Masicera myoidea 

 Desv. The larvse of P. nitela were tunneling through the same plant, or 

 plants in the same hill, as larvse of P. nubilalis, and the latter were only 

 parasitized to a very small extent by the Tachinid. The statement has 

 been made by foreign observers that one reason for the dearth of larval 

 parasitism in P. nubilalis is their protected mode of living within the 

 plant, but in the instance recorded it would seem as though P. nuhilalis 

 should have been parasitized to as great an extent as P. nitela, which at 

 this time was following the same mode of attacking its host plant. 



Parasites of the Pupa. 



In Massachusetts two different species of hymenopterous parasites 

 have been bred from pupse of the European corn borer. These were 

 determined by Mr. A. B. Gahan of the United States National Museum 

 as (Pimpla) Epiurus pterophori Ashm., and {Ichneumon) Amblyteles 

 brevicinctor Say. 



The hymenopterous larva of E. pterophori was found feedmg on the 

 internal juices of a P. nubilalis pupa which had been broken open. The 

 full-grown parasite larva spun a brown silken cocoon and pupated within 

 the remains of its host. Only two of these parasites were bred. 



The adult parasite A. brevicinctor emerged from the fully formed pupa 

 of P. nuhilalis. Two of these parasites were bred during August, 1918. 



No other definite records of pupal parasitism were secured, although 

 several hundred pupse were under observation m life-history cages and 

 during the progress of securing other biological data. 



A single adult specimen of Agrypon sp. (det. Gahan) was found in a 

 pasteboard box cage which contained about a dozen discarded P. nubilalis 

 pupse. The head cap of one of these had been forced ofY, so it is probable 

 that the parasite emerged from this pupa. This cannot be considered a 

 definite record of P. nubilalis parasitism, however. 



A single specimen of Macroce7xtrus sp. (det. Gahan) was bred from a 

 hymenopterous cocoon found in the tunnels of P. riubilalis, near the 

 remains of a P. nuhilalis pupa; but this also cannot be considered a 

 definite record of P. nubilalis parasitism. 



