214 



MR. A. M. ALTSON OX THE LIFE-DISTORY AND 



dilated in the same proportion proved to be the better food, and 

 was occasionally varied with water only. Observation in the 

 open failed to discover any of this species feeding, and in this 

 connection Marshall (3) only observes " both sexes likewise fre- 

 quent flowers for the pnrpose of feeding." It is probable that 

 " honeydew '" constitntes a source of food, as is the case with 

 many Hymenopterons, but was not tested with this species. 



Seasonal Abundance. — From 14tli July, 1919, to the end of 

 January 1920, with a few days' exception, there have l)een active 

 adults in the main cage; the breeding, which, to begin with, was 

 almost a daily occurrence, caused such an overlapping of 

 generations as to bring about this result. Graham-Smith (4) 

 observes: — "The parasite, however, is abundant throughout the 

 season, for it was observed attacking fly larva from 30th May to 

 1st November, 1916." From the observations of the writer, these 

 insects were present in lai'ge numbers from July to October 1919 

 in Regent's Park ; and as the original stoclv bred in the 

 laboratory appeai'ed on 14th July, and taking the average period 

 of the life-cycle a,s 52 days (see Table I.), this gives 24th May as 

 the date upon which the parents of this generation were deposit- 

 ing eggs ; this therefore confirms the above observation. 



Details of Emergence. — Accurate sex details of the daily emer- 

 gence from certain lots were kept from 18th August to 20th 

 September, after which date these had to be abandoned, the 

 breeding opei'ations at this date occupying all available time. 

 Details of daily emergence for the period 3rd to 12th September, 

 corresponding to the period of greatest activity shown in Table I, 

 and a.ffecting laboratory-bred material from the jars No. 1, No. 2, 

 No. 3, No. 4, No. 5, & No. 6 and from No. 7 for one day shown 

 in Table I., are given below in Table III. : — 



Table III. — Details of Daily Emergence. 



These figures merely indicate the early appearance of the males. 

 During the period covered by Table III. tlie average daily 

 contents of the main cage was over 300 individuals of both sexes ; 

 this figure allows for the withdrawal of ovipositing females and 

 admission of daily emergences from all sources. 



Percentage of Parasitization. — Graham-Smith (1), referring to 

 two lots of material attacked by "free" A. mandncator in 1914 

 and bred out in 1915, states: — "In the former it is 60 per cent.. 



