488 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



with tissue paper to prevent the larvae from becoming enmeshed in 

 the cottony fibers. Approximately outdoor conditions as regards 

 temperature and humidity were thus secured. Potted plants infested 

 with aphids and covered with chimney glasses were tried for a time, 

 but did not fulfill the requirements, due to the occasional condensation 

 of moisture upon the glass surface and the tendency of the adult 

 beetles to ascend to the top of the glass and to remain there inactive 

 rather than feeding normally upon the infested plant. 



The points taken up in the investigation were the following: 

 The length of time intervening between emergence and mating and 

 oviposition, the length of the oviposition period, the rate of oviposition, 

 both as to the number of eggs per day and the total number for the 

 entire period, the life histories, and the feeding habits, both in the 

 larval and adult stages. In every case a sufficient number of indi- 

 viduals were started for each species to make it practically certain 

 that at least ten would complete the test, making allowance for una- 

 voidable mortality. The records given for each species, therefore, 

 represent the average for approximately that number of individuals. 



Emergence to Mating and Oviposition 



No great divergence was found to exist between species as regards 

 the length of time intervening between emergence and mating. The 

 range extended from 1.6 days in the case of A. hipunctata to 2.7 days 

 for C. californica. No records were secured of H. convergens due to 

 the fact that all individuals used in the tests were taken from cold 

 storage in the adult stage. From mating to oviposition the variation 

 was from 8.6 days for 0. abdominalis to 11.9 days for C. californica. 

 The minimum period of time for a single individual was 7.0 days in the 

 case of one female of 0. abdominalis and one of C. sanguinea. 



The Period of Oviposition 



The period of time over which oviposition extends is very largely 

 dependent upon the conditions under which the beetles are kept. 

 Under optimum conditions the deposition of eggs takes place daily 

 during a period extending from approximately two weeks after emerg- 

 ence until death. The maximum average was found to be 48.1 days 

 for H. ambigua and the minimum 28.2 days for A. bipunctata. The 

 comparatively low average for H. convergens may be accounted for by 

 the fact that three of the eleven individuals under observation died 

 within two weeks of the beginning of the experiment. Oviposition by 

 one female of H. ambigua extended over a period of fifty-nine days. 



