8 BULLETIN 401, U. S. DEPARTMENT OF AGRICULTURE. 



"watermelons and muskmelons are a luxury; a good melon brings 

 50 cents to $1 at the fruit stands in Honolulu. These products could 

 be raised in certain .sections in quantities large enough to bring them 

 within the reach of every table were it not for the attack of the 

 melon fly," F. G. Krauss, formerly agriculturist of the College of 

 Hawaii, stated (14) in 1005 that were it not for the ravages of cut- 

 worms, plant-lice, and the melon fly melons would be an excellent 

 crop for Hawaii, but that the advantage of the favorable climate of 

 Hawaii was offset by the prevalence of these pests. Blackmail (20), 

 in 1909, places the annual loss to market gardeners as the result of 

 melon-fly attack at three -fourths of a million dollars. Severin (45) 

 writes that " when one stops to consider that the Hawaiian Islands are 

 smaller than the State of Rhode Island, that the principal agricul- 

 tural products are sugar, pineapples, coffee, and rice, one realizes 

 what a tremendous amount of injury this fruit fly causes to the 

 limited vegetable crops grown in the islands." The truth of all the 

 foregoing statements regarding the great damage caused by this pest 

 and its right to first rank among the pests of the market gardener 

 has been corroborated by the writers. It is not possible to over- 

 exaggerate its importance as a serious pest under Hawaiian littoral 

 conditions. 



INJURY. 



Injury due to melon-fly attack is in the nature of deformities re- 

 sulting (1) from punctures made in the epidermis of the host fruit 

 or plant when no eggs are deposited; (2) when the eggs deposited 

 or resulting larvae fail either to develop or to penetrate the tissues 

 deeply; and (3) from the destruction of plant tissue by the un- 

 hindered development of the larvae. While the fruits of the host 

 plant are always attacked with greatest severity, no portion of the 

 plant is immune, particularly when succulent growths are produced 

 by hot, moist weather conditions. 



Injury to the root. — It has been stated (45) that in many locali- 

 ties the seeds of some cucurbits barely germinate before the seedlings 

 are attacked by the melon-fly larvae, which devour the tissues of the 

 stem, causing decay, and penetrate the roots and completely destroy 

 the plant. This type of injury (PI. I) is by no means the most 

 common, but has been observed by the writers on many occasions. 

 The writers have never known the roots of seedlings of any host 

 other than the watermelon to be thus attacked, and then only when 

 the plants were very succulent. Entire fields of watermelons have 

 been destroyed by such attacks during the warmer parts of the year 

 in a badly affected area. At other seasons and in localities more 

 isolated from habitations, or where no host fruits have been grown 

 for some time, seedlings are not usually affected below the ground. 



