392 joirxai. of economic entomology [vol. 7 



Mating Observations 



With all the study of the flies that we had done in Hawaii, their 

 copulation had not been observed. In most instances, in the study of 

 any economic species, a knowledge of the mating habits is very impor- 

 tant. This is especially true in the present case, since we then knew 

 when the flies were ready to reproduce. We first saw the flies mating 

 when they were six days old, but later observation on the second brood 

 showed that they begin mating on the same day that they emerge, in 

 fact, when they are only about six or eight hours old. 



A detailed account of these observations may be of value here. 

 The male during copulation, stands on top of the female, his fore feet 

 on either her head or thorax; the middle feet on the outspread wings; 

 and the back clasping her abdomen. The mating, during the first day, 

 was for very short periods, not more than half a minute at a time. It 

 resembled very closely that of the ordinary house-fly. However, 

 during the second day, they remam together for about four minutes, 

 and, on the third day the average time required for copulation was a 

 little over 18 minutes. Mating, evidently, is continued from time to 

 time for a considerable period, since it was observed in the first instance 

 on the sixth day. 



Larva-positing 



Mr. Frederick Muir, of the Hawaii Sugar Planters' Association, by 

 careful dissection, estimated the number of eggs which the flies were 

 able to produce. In one case he found 570 fully developed eggs in the 

 uterus, and many others filling the fallopian tubes and ovaries. Thus 

 the number of young possible for a fly to produce is upwards of 1,000. 

 Mr. Muir also discovered that the eggs hatch while still in the uterus 

 of the fly, and are deposited as living maggots. This is particularly 

 favorable to their multiplication, since the little, active maggot at 

 once enters the grub, and escapes the myriads of ants that swarm over 

 the canes. 



While these flies are rather quiet they appear to be very reticent 

 about letting one see them larva-posit. After continued observations 

 I was able to see this interesting process several times. The female 

 was first noticed carefully examining one of the minute pin-holes, made 

 by the borer grub through the rind of the cane. Her head was held 

 very low, with the antennae close against the surface of the cane. It is 

 well known that the organs of smell in insects are located in the anten- 

 nae; so she was evidently smelling to decide whether a borer grub was 

 near the opening. In about two seconds she touched the tip of her 

 abdomen to the surface of the cane, twice, and deposited two active 

 maggots. They were side by side, about 1 mm. from the pin-hole, and 



