HABITS OF TWO PAKASITES OF BLOW-FLIES. 



199 



arfa with 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 successfully reared by this means. 



Several methods of presenting the larv?e for parasitization were 

 tried, the original ohject being the attainment of those conditions 

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

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

 that it became necessary to repi'oduce 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 projrress 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 necessary stock for shipment. 



Life-History and Habits of Alvsia mandl cator Panz., 

 AND Hosts. 



Introductory.' — Alysia manducator Panz. was selected by 

 Latreille as the type of his gewwii 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 

 obsei've it under natural conditions were very limited. 



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

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

 33 days and upwards, with a. mean average of 52 days, but varie.i 

 considerably for some leason even amongst those of the same 

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

 extraoidinary variation, and refers to nine lots of material para- 

 sitized in the laboratory. Graham-Smith (1) records an 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 



Egg of ^. wa?ic?^tca^^or, from ovary. Size 'GToX'loO mm. X61. Original. 



other] with the micropyle narrowly attached and having tlie 

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



Text- figure 1. 



