138 Kansas Academy of Science, 



HABITS OF LYSIPHLEBUS sp. 



By C. H. WiTHiNGTON, Kansas State Agricultural College, Manhattan. 



TOURING the past summer I noticed that some of the corn- 

 -^-^ fields about Lawrence, Kan., were badly infested with 

 the corn-leaf louse. Aphis maidis Fetch. At this time I was 

 greatly interested in insect parasitism, and so watched closely 

 for any evidence of it in this species. On the afternoon of 

 August 10 my search was rewarded by the finding of seven 

 parasitized specimens of Aphis maidis sticking to the tassel of 

 a corn-stalk. These were taken to my room, where I could 

 easily watch the emergence and secure the parasites. On 

 August 12 two specimens of the genus Lysiphlehus emerged 

 and were promptly mounted for study. Nothing came from 

 the remaining five. . Thenceforward I watched the fields closely 

 for further parasitism, but saw no more until September 20, 

 when, while collecting on the college farm at Manhattan, Kan., 

 I found a female of Lysiphlehus sp. on volunteer corn, with 

 some specimens of Aphis maidis that clearly showed evidence 

 of parasitism, and on the following day I found hundreds of 

 parasitized lice dead and dying on the under sides of the leaves 

 and on the inner husks of the corn-stalk. At Lawrence the 

 parasitized individuals were found only on the young tassels 

 and the two upper leaves, while at Manhattan, six weeks later, 

 they were confined to the leaves and husks. As the season 

 ^vanced the lice left the leaves and the infestation came to 

 be limited to the inner husks about the ear, becoming so great 

 here that these were frequently entirely covered with aphids. 

 By the first of October winged individuals were very plentiful, 

 and from this time forward the infestation decreased until, 

 with the coming of the first frosts, about the 1st of November, 

 it disappeared from here as well. At this stage I became very 

 anxious to know where the lice had gone and what the para- 

 site was going to do for a host, but, in spite of close watching, 

 am unable to answer either of these questions satisfactorily. 



I found wingless Aphis maidis on well-grown volunteer 

 wheat as late as November 24, but from November 9 the speci- 

 mens under observation have been torpid. The majority of the 

 embryo parasites inhabiting the lice on the 1st of November 

 have not emerged, but also appear to be dormant. 



