320 Kansas Academy of Science. 



RELATIVE RATE OP INCREASE. 



From the preceding data on Siphonophora rofioe it is readily cal- 

 culated that the progeny of a single louse at the end of 42 days will 

 be 929 agamic females. 



The average length of time for the Ephedrus to pass from egg 

 to adult has been found to be 21 days. One fertilized female suc- 

 cessfully parasitized an average of 53.2 lice, 50.2 per cent, of which 

 were females. From this it is readily calculated that the total pro- 

 geny at the end of 42 days would be 1529 individuals. Theoretically, 

 the progeny of one Ephtdrris shows an increase of 597 above the 

 progeny of one iSiphonophora roi^ce at the end of 42 days. 



Thus the parasites would be able to control the ravages of the 

 rose "green fly." This shows to a certain extent the economic 

 value of these parasites to the florist, for he could avoid the extra 

 expense and labor of fumigating by introducing the Lysiphlebus 

 cerasaphis and Ephedrus sp., which have been proven beyond a 

 doubt to be an efficient natural check to the rose aphid under good 

 greenhouse conditions. 



In conclusion, my thanks are especially due to Dr. T. J. Headlee, 

 under whose directions these experiments were performed and this 

 paper written. I wish also to express my obligations to Miss H. E. 

 Branch for the drawings, and Mr, Charles T. Brues, of Milwaukee 

 Museum, for determining the Lysiphlebus cerasaphis (Fitch). 



