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



PARASITES. 





Hawaii has no native parasites that attack the melon fly, but the 

 Hawaiian Board of Agriculture and Forestry has introduced a para- 

 site froni India. This parasite x was introduced at Honolulu during 

 the early part of 1916. and has been reared and distributed in large 

 numbers, but it is not known yet whether it will check the ravages of 

 the melon fly in a practical manner. It has become established, how- 

 ever, and promises to be useful. 



ARTIFICIAL CONTROL. 



Individual growers of vegetables in Hawaii are likely to be dis- 

 couraged in the application of remedial measures for the control of 

 the melon fly. Host fruits are grown in rotation in the numerous 

 garden spots and market-garden areas chiefly by uneducated orien- 

 tals, who do not appreciate the necessity for a united fight against 

 the fly. The usual custom among these laborers is to permit infested 

 fruits to decay in the field. In certain uncultivated areas the wild 

 Sycos and Chinese cucumbers run wild and furnish fruits in which 

 the melon fly can breed throughout the year, even though no culti- 

 vated crops are grown. This abundance of cultivated and wild host 

 fruits, coupled with a climate favorable for rapid multiplication, 

 produces many adult flies which spread in all directions to render 

 valueless all remedial measures except those that involve protective 

 coverings for the fruits. 



It thus happens that no artificial control measures have been 

 applied successfully in controlling the melon fly under Hawaiian 

 conditions. The only means now employed to safeguard fruits is 

 that of protecting the young fruits with seme type of covering until 

 they are large enough to withstand attack. Trapping adults has 

 proved a failure, and killing them by spraying thus far has given 

 poor results. If all growers would cooperate systematically (1) in 

 the destruction of the- eggs and larva? by submerging infested fruits 

 in water or by boiling and (2) in the destruction of the adults by 

 spraying, the value of spraying with a poisoned bait and of covering 

 the young fruits would be enhanced to a point where either might 

 be sufficiently effective to be recommended as satisfactory. But so 

 long as the cultivation of host plants is largely in the hands of 

 orientals and others who do not appear to be amenable to instruc- 

 tion as modified by western standards, no relief can be expected. 



Since adult melon flies do not deposit eggs for 2 to 1 weeks after 

 emergence during the summer, and only after relatively longer periods 



1 Optus fletcheri Silv. 



