24 BULLETIN 643, U. S. DEPARTMENT OF AGRICULTURE. 



of about 71° F., many adults may not lay until 44 days after emer- 

 gence. The season of the year and the nature of their food have an 

 influence upon the rapidity with which eggs are formed. 



But once the female fly begins to lay eggs, she may continue to do 

 so throughout life. The largest number of eggs laid by any female 

 in confinement is 687, but 1,000 probably may be laid by vigorous 

 long-lived flies. While 37 is the largest number of eggs laid by a 

 single individual during any one day, the number varies, and may 

 be as few as 1. On many days no eggs are laid. Unlike the female 

 of the Mediterranean fruit fly, which lays a few eggs almost daily, 

 the female melon fly lays more eggs per day, but at greater intervals. 

 Thus one fly deposited 14, 19, 13, 29, 16, 19, 16, 12, 17, 7, 9, 16, 7, 12, 

 37, 25, 24, 21, 28, 6, and 18 eggs, respectively, per day during the first 

 three months (summer months) after depositing her first eggs; she 

 laid no eggs in fruits until she was 51 days old, and, after she began 

 laying, laid eggs on only 21 out of 90 days. During the seventh, 

 eighth, and ninth months of her life (winter months) she deposited 

 10, 2, 18, 14, 15, 20, 13, 9, and 3 eggs. 



Female flies can resume normal egg laying after periods of scarcity 

 of host fruits. Females that have not been given an opportunity to 

 lay eggs within fruits for periods ranging from 3 to 9 months after 

 emergence have begun to deposit eggs at a normal rate as soon as 

 fruits were placed with them in the laboratory rearing cages. 



WHY THE MELON FLY IS A SERIOUS PEST. 



The melon fly is a serious pest in Hawaii because it finds in the 

 coastal areas a favorable climate and plenty of food. Regardless of 

 the great discouragement due to its ravages, the oriental market 

 gardeners, and others to a less extent, plant its host vegetation in 

 rotation on the same or neighboring plats of ground. ~No attempt is 

 made to prevent the flies from maturing in infested fruits. The de- 

 caying and infested fruits of the cucumber crop, for instance, are 

 left on the field that is to be planted to tomatoes, or the flies develop- 

 ing from the cucumbers migrate to attack the melons just coming 

 into bearing in the near-by field. N/o system of control, aside from 

 covering successfully a small portion of the fruit that sets, is prac- 

 ticed. 



It thus happens that large numbers of adults mature, and, as the 

 climate is favorable, they multiply rapidly. During the warmest 

 Hawaiian weather, when the mean temperature averages about 79° 

 F., the egg, larva, and pupa stages may be passed in as few as 12 or 

 as many as 29 days, according to the individual and its host. The 

 complete life cycle is subject to great variation, according to the 



