140 Kansas Academy of Science. 



mometer records were kept. Seventeen of the cages came 

 through without accident. At a mean daily temperature of 

 62.6 degrees F. the parasite passed from egg to adult in an 

 average of 16.8 days, with 13 to 23 days as extremes. A 

 single female successfully parasitized from 1 to 147 indi- 

 viduals, with an average of 34. 



We then made an effort to determine what other hosts this 

 species of Lysiphlebus could use. We tried fertilized females 

 on Hyalopterus ai^ndinis Fab., Siphocoryne avense, Thomas, 

 Aphis cucumeris Thomas, N ectaropliora calendulse Morrell, 

 Nectarophora prunicola Ashmead, Chaitophoms negundinis 

 Kalt., Nectarophora chrysanthemi Oestl., and Toxoptera gra- 

 minum Rond., but found they worked readily only on Aphis 

 cucumeris, Siphocoryne avenss, and Toxoptera graminum. In 

 case of the last, under a mean daily temperature of 60 degrees 

 F. the parasite passed from egg to adult in an average of 17.5 

 days. 



When we consider that this Lysiphlebus sp. lives readily at 

 the expense of Toxoptera graminum, which has so lately shown 

 its ability to destroy wheat and oats of immense areas, be- 

 sides being able to subsist on other hosts that are seriously in- 

 jurious to human welfare, it is clear that this species is worthy 

 of careful study from a purely economic view-point, to say 

 nothing of its scientific interest. 



