HABITS OF TWO PAKASITES OF BLOW-FLIES. 199 



aipa witli a quantity of feces adhering to it, and was placed on a 

 piece of liver on fine damped soil in a tray ; artificial heating was 

 applied, and the species was successfnlly reared by this means. 



Several methods of presenting the ]arv?e for parasitization were 

 tried, the original object being the attainment of those conditions 

 in which they would be an easy prey for the Braconid's attack. 

 It was found tliat free larvae severely damaged the females, so 

 that it became necessary to reproduce conditions as nearly natural 

 as possible. 



In the case of the Chalcid, host puparia — in a proportion of 

 20 per female — were placed in small receptacles in the cages and 

 left there for ten days for parasitization. The puparia were 

 obtained from the trays by sifting ; this rough handling did no 

 appreciable damage. 



The breeding operations were in progress from July to the 

 end of December ; from July to the middle of September all lots 

 of parasitized material were reared to maintain supplies of parent 

 generations for the cages ; after this period the parasitized 

 material was exposed on the balcony of the College to hibernate 

 and form the necessaiy stock for shipment. 



LiFE-HlSTOKY AND HaBITS OF ALTSI.-i iMAXDVCATOB PaNZ., 



AND Hosts. 



Introductory. — Alysia manducator Panz. was selected by 

 Latreille as the type of his gewwH Alysia, and belongs to the group 

 Exodontes of the family Braconidae. 



It should be noted that the following account is mainly based 

 upon observations of this insect in captivity; opportunities to 

 observe it under natural conditions were very limited. 



The Length of the Life-cycle. — The length of the life-cycle from 

 agg to adult is, under suitable conditions of temperature, from 

 33 days and upwards, with a. mean aver.age of 52 days, but varies 

 considerably for some leason even amongst those of the same 

 parent and under the same conditions. Table I. shows this 

 extraordinary vai'iation, and refers to nine lots of material para- 

 sitized in the laboratory. Graham-Smith (1) records a,n instance 

 in which the life-cycle took only 25 days. 



The Egg. — The egg (text-fig. 1) is very small, cylindrical, 

 tapering, and broadly rounded at one extremity, broadest at the 



Text-fio-ure 1. 



^<^S^ oi A. manducator, horn o\-A.vy. Size '675 X '150 mm. X61. Original. 



otherj with the micropyle nai-rowly attached and having the 

 appearance of a large protuberance. It is just visible to the 



