364 Journal of Agricultural Research voi. iii.no. s 



PUPiE 



SECURING MATERIAL 



In obtaining a colony of fruit flies the usual method is that of placing 

 infested fruit over sand in some kind of a securely screened container. 

 The writers have found that the easiest method of securing large quan- 

 tities of pupae from which to rear adults and pupal parasites is to use any 

 sort of contrivance which will keep the infested fruits free from the sand 

 and at the same time bring the emerging larvae to a central point, where 

 they may be quickly and easily gathered. If the fruit is allowed to come 

 in contact with the sand, the latter becomes so saturated with the juice 

 of the decaying fruits that it can be freed from the pupae only with con- 

 siderable effort and expenditure of time. Plate XLIV, figure 2, repre- 

 sents the first contrivance of this kind used by the writers. It is made 

 of galvanized iron, 36 by 18 inches, with a depth at the lowest point of 

 24 inches. On the inside, 2 inches from the top, there are narrow sup- 

 ports, which hold in place a tray with handles at both ends and a bottom 

 of galvanized-iron screen with a >2-inch mesh. The larvae emerging from 

 the fruit instinctively work their way downward and fall through the 

 screen, and are carried thence by gravity and their own movements 

 through the outlet below into the small container. This arrangement 

 works well with very nearly all the host fruits likely to be used as a 

 source of pupse, such as Mumsops clangi, the rose-apple {Etigcnia jambos), 

 the kamanis {Terminalia cattapa and Calophyllum inophyllum), and the 

 strawberry guava (Psidium cattle yanum) . Such fruits as the mango 

 (Mangifcra indica) can be used, but they yield so much juice that the 

 inside of the frame becomes so wet that the escaping larvae often pupate 

 without falling through into the container below, and the sand in the 

 latter becomes more or less saturated. 



Previous to the adoption of this method of securing pupae, there was 

 in general use, both by the Hawaiian Board of Agriculture and Forestry 

 and by the writers, a shallow box about 14 by 12 by 3 inches, ordinarily 

 used by florists. The bottom of this box was covered to a varying depth 

 with sifted sand, on which were placed the infested fruits. During the height 

 of the season of 1913 from five to eight men were employed by the Terri- 

 torial and Federal authorities in daily removing infested fruits from one 

 box to another containing fresh sand, and in sifting for the pupae the sand 

 over which the fruit had lain for 24 hours. Besides requiring much time, 

 the prolonged sifting necessary to free the pupae injured many of them. 

 The writers are now using a frame 6 by 3 feet and 3 feet in depth similar 

 to that shown in Plate XLIV, figure 2. The use of a sufficient number 

 of cheap wooden frames covered with tin well painted will make it 

 possible for one man in several hours to do the daily work formerly 

 requiring six to eight men. 



An adaptation of the old box system has been found useful when it has 

 been desirable to keep separate the pupae from small lots of fruit gathered 



