THE MELON" PLY. 25 



longevity of the adult. Since one female fly has been known to live 

 431 days, it is evident that the complete life cycle from the laying of 

 the egg to the death of the fly may be 443 to 460 days when the im- 

 mature stages are passed during the warmer portions of the year. 

 At an average mean temperature of about 68° F., which is the coolest 

 temperature found in Hawaii where fruits are available in numbers 

 for study, the immature stages are passed in 40 to 45 days. It is 

 difficult to state just what the variation in the life cycle may be in 

 colder climates, but it may range between 3 and 4 months. 



This rapidity of increase throughout the coastal regions permits 

 from 8 to 11 generations of the melon fly a year, when a generation is 

 considered to extend from the time the egg is laid until the female of 

 the next generation begins to deposit eggs. As the females are 

 capable of living many months and of depositing eggs at frequent 

 intervals throughout life, the generations become hopelessly mixed. 

 It is possible for a female ovipositing on January 1 to be still alive 

 and laying eggs the following January along with the progeny of 

 11 generations of her descendants. It is, therefore, small wonder 

 that the melon fly, under such favorable conditions, swarms through- 

 out the market gardens of Hawaii and leaves little unaffected that is 

 not protected by man. 



CONTROL MEASURES. 



NATURAL CONTROL. 



No agencies at present are working in the Hawaiian Islands to 

 bring about, even periodically, a very large natural reduction in the 

 abundance of melon flies. The mortality among the immature stages, 

 or among the adults, is not sufficiently high to be of practical value, 

 although sometimes 90 per cent of the larvae may be found dead in 

 certain decaying fruits. 



In climates colder than that of the Hawaiian coastal areas mor- 

 tality due to cold temperatures will play a particularly active part 

 in reducing the pest. While the cooler weather of the winter months 

 does prolong the period of development throughout the coastal re- 

 gions, the long life of the adult flies and the capacity of females for 

 continued egg-laying make it difficult for market gardeners to benefit 

 to any marked extent from the effects of cool weather if they allow 

 their fruits to remain unprotected. The cooler weather in the more 

 isolated gardens holds down the number of adults and limits their 

 activity to a fewer hours during the day when it is warm enough for 

 them to attack fruits, and in this way makes possible greater success 

 in saving fruits by the use of various protective coverings than fol- 

 lows the use of the same measures during the summer months. 



