HABITS OF TWO PARASITES OF BLOW-FLIES. 



233 



No signs of Chalcid infestation was observed. The female may 

 have died within a few days of tlie start of the experiment. 



The foregoing experiments show that, nnder certain conditions 

 — and with fractiu'ed puparia — JVasouia can snper-parasitize 

 A. manducator lined and inhabited puparia, and in two 

 instances three kirvsB reached full growth. 



Whilst experiment No. 2 was developing, experiments into 

 other directions w ere undertaken. 



It has been [)reviously stated that blow-fly larva? upon 

 recovering from "temporary paialyfsis" are stimulated to pupate 

 and to escape from tlie females of A. manducator. It was there- 

 fore decided to ascertain to what depth such larva? worked their 

 way into the soil. 



Experiment N^o. 3. — A wooden box with a sliding lid was 

 requisitioned. One end was removed, and the sliding lid sawn 

 across into strips an inch wide. Thus when placed upright with 

 the remaining end as the base of the box, the original base 

 formed one side and the sliding lid in strips the other, with the 

 original sides as ends. 



This box was then gradually filled with soil which, during the 

 building up of the requisite depth, was twice subjected to running- 

 water to damp it. Seven inches of soil wei'e eventually put in. 

 On the same day — 9th January, 1920 — pieces of liver upon which 

 fly-larva? had been feeding were placed on the surface of the soil 

 in a compact mass. One female A. mandiicator was then caught 

 in a tube from the main cage. The mouth of the tube was then 

 held over the liver until the female was stimulated to descend 

 upon it. As soon as she got on to it, she started examining it for 

 larvfe. 25 of these, about three-quarters to full grown, were at 

 hand ; they were placed near the female, one at a time, so soon 

 as she had oviposited into each of them. In three instances she 

 attacked twice, having failed to come in contact with the sub- 

 stitutes, and in each case the latter Avere withdrawn and given 

 to her a second time. It took 57 minutes to get the 25 larva^ 

 parasitized. The female was moved back into the tube and 

 given a smear of food on the cork. She was allowed to rest in 

 the tube for 20 minutes. In the meanwhile another 25 larvpe 

 had been collected. The female was noAv released again, and the 

 same process started, but she only attacked one of these larvie ; 

 and although others were placed near her, she could not be 

 induced to attack any more, and after 26 minutes the experi- 

 ment was given up for the day. The i-emaining 24 larvfe of the 

 second lot were returned to their breeding dish, and the female 

 caught and left in the tube with food. 



No further action was taken for the next two days. On 12th 

 January, 1920, the experiment was continued. The above female 

 was found dying ; another was therefore removed from the cage, 

 and at 2.30 p.m. it w^as set to work on 25 larvre as before, but 

 at 3.25 P.M. it suddenly became dark, and the female refused to 

 oviposit any more. In this time — 55 minutes— she had dealt with 



