THE MELON FLY IN HAWAII. 25 



mean temperature for January was 71° F. during 1916 and the mean 

 relative humidity 78.5 per cent, did not bvi posit until February 17, 

 although they were given abundant opportunity. In this instance no 

 eggs were deposited until the females were 44 days old. 



In the case of the adults emerging January 3, 1916, and fed %n 

 papaya and water, dissections were made of the ovaries of females 

 at frequent intervals from the time of emergence until egg laying 

 began. The appearance of the ovarian tubes dissected from females 

 1, 23, 33, and 38 days after emergence is shown in Plate XXIII. At 

 no time were the ovarian tubes found to contain a well-graduated 

 series of eggs, as is found in many insects, or as found by Dr. Illings- 

 worth in the ovarian tubes of the apple maggot {Rhagoletis poTno- 

 nella Walsh) and the cherry fruit fly (Rhagoletis fausta O. S.) 



From the observations made upon the development of the eggs of 

 melon flies fed upon the juice of cucumbers it seems reasonable to 

 conclude that under natural conditions egg deposition commences 

 almost as soon as the eggs have peached maturity in the egg tubes. 



Whether confinement does retard egg development has been diffi- 

 cult to determine, but development of eggs within the ovarian tubes of 

 the Mediterranean fruit fly progresses so rapidly in confinement under 

 like conditions that the writers conclude that confinement of the 

 female melon fly in large jars, with plenty of food, does not retard 

 development. 



Portmn of plant selected. — The female fly deposits eggs at ran- 

 dom in various portions of the host plants, the portion selected de- 

 pending largely upon the stage of growth and variety of host. In 

 young seedlings, particularly succulent watermelon seedlings, eggs 

 are deposited within the crown of the plant or in the petiole of the 

 leaf. As the cucurbits develop runners the eggs may be deposited in 

 these, usually near the growing tip or less frequently farther back in 

 the tougher, older portions. The older vines are seldom made use of 

 for oviposition, and of the cucurbits, the vines of the pumpkin, 

 squash, momordicas, and cucumbers are least attractive. No oviposi- 

 tion has been noted in tomato or bean stalks. The female prefers 

 to oviposit within the unfertilized, still undeveloped ovaries of all 

 cucurbits, with the exception of the young cucumbers, which are not 

 attacked until the fruits are from 2 to 4 inches long. Ovipositing 

 into the male bloom of squash and pumpkin is so universal that it 

 would appear that this portion of the plant is as attractive to the 

 female as the unfertilized ovaries. Oviposition has never been ob- 

 served to occur in the male bloom of watermelon, cantaloupe, Mo- 

 mordica spp., or the bloom of tomatoes, cucumbers, and beans. Even 

 after pumpkins and squashes become so well developed that the 

 melon-fly larvae can not penetrate and cause their destruction, the 



