180 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



The color also varies considerably, although the color-pattern 

 is fairly constant, the variation being one of intensity in shade 

 rather than otherwise. 



Diaeretus rapae Curtis. 



Aphidius rapse Curtis, Macintosh, Book of the Garden, n, 1855, 



p. 194. 



Trioxys piceus Cresson, U. S. Dept. Agric. Report, 1879, p. 260. 

 Lipolexis piceus (Gresson) Ashmead, Proc. U. S. Nat. Mus., 



1888, p. 671. 



Aphidius brassicse Marshall, Spec. Hymen. Europe, 1891, p. 597. 

 Aphidius rapse (Curtis) Marshall, Spec. Hymen. Europe, 1891, 



p. 615. 



Aphidius brassicse, Marshall, Trans. Ent. Soc. London, 1897, p. 63. 

 Aphidius rapse (Curtis) Marshall, Trans. Ent. Soc. London, 



1897 p. 71. 



Preliminary to a discussion of the synonymy, it seems appro- 

 priate to give here some observations on this species made by 

 the writer. It was exceedingly abundant in Maryland the 

 past season, affording excellent opportunity for study. On 

 May 8 several cabbage plants that were covered with lice 

 (Aphis brassier} were brought by a truck grower to the 

 experiment station and examination showed that the great 

 majority of the lice were already parasitized. Three of the 

 plants were placed in a cage and within the next week over 

 1,500 parasites emerged. A careful count of the antennal 

 joints of 328 of these specimens resulted as follows: 



13-jointed antennse 6 females. 



14-jointed antennae 169 females. 



15-jointed antennas 21 females. 



16-jointed antennas 22 males. 



17-jointed antennas 108 males. 



18-jointed antennas 2 males. 



The species have been credited by Ashmead with 14-joiuted 

 antennae in the female and 17-jointed in the male, and nothing 

 is mentioned about any variation, although Cresson in his 

 description gave the female antennse as 13-jointed. In order 

 to ascertain whether but one species was represented, a 

 female having 14-jointed antennse was placed, June 5, on a 

 louse-infested plant known to be free of parasites. She 

 began ovipositing at once and June 20-21 twelve specimens, 

 all of which were males, were taken from the cage. This 

 female was not known to have been fertilized, and since 

 parthenogenesis is known to exist in Lysiphlebus tritici, the 



