PROC. ENT. SOC. WASH., VOL. 23, NO. 6, JUNE, 1921 137 



In the spring of 1920, most of the larvae of P. nubilalis col- 

 lected in southern France were shipped to the corn-borer 

 laboratory in Massachusetts. Consequently, few parasites 

 were bred in the laboratory at Audi anil the data secured in 

 regard to the later phases of their life histories is somewhat 

 fragmentary. From the information available it appears that 

 the larvae of Zenillia roseanae emerge from the hibernating 

 caterpillars of the borer about a month before the latter begin 

 to pupate; but that the duration of the pupal and preoviposition 

 periods in the case of the parasite are so much longer than in 

 the case of the host, that the adult females of the Tachinid are 

 not ready to oviposit until the young caterpillars of Pyrausta are 

 present on the corn plant. 



The first puparium found under outdoor conditions in 1920 

 was taken from a corn stalk in the laboratory garden on March 

 24; it was then freshly formed. 



In caterpillars of the summer generation, larvae of Zenillia 

 roseanae in stage II were first found on July 28 and last found on 

 August 12, after which time no further dissections of the summer 

 generation caterpillars were made in this region. The first 

 puparium of the summer generation of this species was found in a 

 flower stalk of the corn plant on August 3, the last on August 

 17, on which date a puparium from which the adult had already 

 emerged was also collected. The duration of the pupal stage 

 in the summer generation appears to be considerably shorter 

 than in the hibernating generation but on this point we have not 

 yet secured any exact information. 



Few dissections of caterpillars of the autumn generation were 

 made in 1920, but in a lot collected on October 3 a larva of Z. 

 roseanae in the first stage was found in the fat body of a Py- 

 rausta caterpillar. 



The most important practical point determined by the inves- 

 tigations undertaken up to the present on the seasonal history 

 of 7,enillia roseanae is that this parasite has a seasonal historv 

 synchronous with that of the host in southwestern France, having 

 like the latter two generations a year of ivhich the second is passed 

 in the larval stage in the hibernating caterpillars of the borer . 



OTHER HOSTS. 



In the work of Brauer and Yon Bergenstamm already cited, 

 Zenillia roseanae is recorded as a parasite of the well-known 

 grape pest Conchy/is roseana Hw. As we have had occasion to 

 examine only a small number of the caterpillars of the host in 

 question we are unable to confirm this record. 



SECONDARY PARASITES.. 



On April 14, 1920, a puparium of this species was found which 

 was filled with the larvae of a chalcid parasite; the puparium 



