316 



Kansas Academy of Science. 



weeks, in the one where the parasites were not found it was neces- 

 sary to fumigate every week, and sometimes two evenings in suc- 

 cession. Even this was not sufficient to keep them under complete 

 control. 



To determine what hosts Lys'phlebus cerasaphis can use, fer- 

 tilized females were tried on Siphonophora rosce (Reaumur), the 

 daisy aphid, Toxoptera graminum (Rodani), Macrosiphum sp., 

 Rhopalosiphmn dianthi (Shrank), and Myzus persicm (Sulzer), 

 but it was found that they worked only on Siphonophora rosce. 



EFFICIENCY. 



To determine how many aphids one parasite could kill, cages 

 were prepared, as follows: A small rose plant was set in each of 

 five nine-inch flower pots; on each plant were placed 200 lice; the 

 plant was then, covered by a cloth-capped lantern globe, and one 

 pair of newly emerged parasites introduced. During the entire 

 experiment careful moisture and maximum and minimum ther- 

 mometer records were kept. 



&3 



200 

 200 

 200 

 200 

 200 





5-9 

 5-9 

 5-9 

 5—9 

 5-9 



^•S, 



5-9 

 5-9 

 5-9 

 5-9 

 5-9 



«3 



c? 9 



d 



5-19 

 5—20 

 5-20 

 5-20 

 5-19 



5-24 

 5-25 

 5-26 

 5-25 

 5-25 



d 



3 (B 



2 3 



5-26 

 5—26 

 5-27 

 5-26 

 5—26 



Average. 



ti c 



2 ^ 



52 

 97 

 61 

 39 

 105 



21.2 



(t 2 



c ^■ 



49.6 



So? 



75.4 

 75.3 

 73.8 

 75.3 

 75.3 



75.4 



> 



2 "< 

 "£ 



C (B 



72.4 

 72.4 

 73.1 

 72.4 

 72.4 



72.5 



It was found that one fertilized female of Lysiphlebns cerasa- 

 phis at a mean daily temperature of 75.4 degrees F. and under a 

 mean daily moisture of 72.5, successfully parasitized from 39 to 105 

 Siphonophora rosfe, with an average of 70.8. The length of time 

 required for the parasite to pass from egg to adult was 16 days, 

 with 15 to 17 days as extremes. It was also found that of the 354 

 parasites which emerged from this experiment, 70 per cent , or 

 248, were females. 



To determine the rate per day of reproduction, the number pro- 

 duced and the length of life of Siphonophora rosce, four cages 

 were prepared, and handled as follows: In each of four six-inch 

 flower-pots, small rose cuttings were planted, and on each was 

 placed a young aphid born February 4, 1908; each plant was then 

 covered by a cloth-capped lantern-globe. When the aphids began 



