Abstract
To eradicate the melon fly, Dacus cucurbitac COQUILLETT, from Kikai Island, Kagoshima, sterile insects which had been mass-reared were released. In this procedure, a cylindrical plastic egging receptacle was used for collecting the eggs. The receptacle was perforated and contained a 50-mesh nylon net as well as pumkin juice with or without dilution with water (50%). During the 2nd to 4 th generation of mass-rearing, a larger amount of eggs was laid in the receptacle containing non-diluted juice than in that containing diluted juice. However, in the 10th generation there were no significant differences in the amount of eggs laid between the two treatments. The amount of eggs laid was larger in the receptacle containing juice made of the squash cultivar "Tetsukabuto", followed by "Yoron" and "Ebisu". The amount of eggs laid rapidly increased from the 2nd to the 5th generation by 10 to 20 ml/cage/week in each generation. After the 6th generation the amount of eggs gradually increased by about 10 ml/ cage/week in each generation. A larger amount of eggs tended to be laid in the receptacle that was placed in the bottom of the adult-rearing cage. This tendency became more distinct after the 10th generation. These results suggest that some changes in the oviposition pattern of the females in the course of mass-rearing may have possibly occurred.
