Biological Papers. 



319 



this it cuts a neat circular opening at the caudal end of the body, 

 through which it promptly emerges. 



DISTRIBUTION. 



The writer first found these parasites at Manhattan, Kan., in Mr. 

 Moore's greenhouse, November 11, 1907; later in two greenhouses 

 in Topeka, Kan., April 12, 1908; and one in Lawrence, Kan., April 

 13, 1908. la Mr. Moore's and the two greenhouses in Topeka the 

 Lysiphlehus cerasaphis was also present, while in the one at Law- 

 rence there were no signs of Lysiphlehus cerasaphis, but a number 

 of the Ephedrus. The lice in this house were two to every plant. 



EFFICIENCY. 



To find the number of aphids a single Ephedrus could parasitize, 

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

 four nine-inch flower-pots; on each plant about 200 lice were placed; 

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

 pair of newly emerged Ephedrus introduced. During the entire 

 experiment careful moisture and maximum and minimum ther- 

 mometer records were kept. 



2; 

 P 



u 



go 



200 

 200 

 200 

 200 

 200 



o 



5-9 

 5-9 

 5-9 

 5-9 

 5-9 



d o 

 £•3 



5—9 

 5-9 

 5-9 

 5-9 

 5-9 



C? 9 





5-21 

 5-22 

 5-22 

 5-20 

 5-22 



5-29 

 5-31 

 5-30 

 5-29 

 5-31 



b 

 3!f 



§3 

 : 3 



5—30 

 6- 1 

 5-30 

 5-30 

 6- 2 



Average . 



2 c 

 2 a* 



■d 



63.2 



23.4 



22.9 



r 



ft.'" 



•<! O 



3 



21 



> 



2 (t> 

 p ft. 



75.9 

 80.0 

 75.9 

 75.9 

 81.1 



77.7 





73 3 

 73.6 

 73.3 

 73.3 

 73.3 



73.3 



It was found that one fertilized female of Ephedrus r(?sa? success- 

 fully parasitized under a mean daily temperature of 77.7 degrees 

 F., and a mean daily moisture of 73.3, from 19 to 38 Siphonophora 

 roscB, with 53.2 as an average. The length of time required for the 

 parasite to pass from egg to adult was 21 days, with 20 to 22 days 

 as extremes. Of the 266 parasites which emerged, 52.2 per cent., 

 or 139, were females. 



To determine what other aphids the Ephedrus could use for a 

 host, fertilized females were tried on Siphonophora rosoB ( Reaumur) , 

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

 Rhopalosiphnm dianthi (Shrank), and Myzus persicce (Sulzer), 

 but it was found they used Siphonophora rosm only for a host. 



