54 BULLETIN 491, U. S. DEPARTMENT OF AGRICULTURE. 



melon fly in this oil, although they have had traps hung throughout 

 the infested district for many months. Severin was not able to 

 catch ;t sufficient number of melon flies in various oils to feel that 

 they were in any way actually attracted. He used the following 

 oils: Citronella. turpentine, coconut, whale, fish, kerosene about 

 120° Baume, gasoline about 86° Baume, and benzine about 63° 

 Baume. Turpentine, gasoline, and benzine caught no flies. The 

 other oils, exposed over a 5-day period, caught from 2 to 5 individ- 

 uals, representing both sexes. 



Ordinary flytraps baked with diluted molasses and hung about 

 infested fields were found by Severin to be worthless. 



Protection of fruit by covering. — The attack upon cucurbits of 

 all varieties. is so universal in Hawaii that the female bloom in all 

 species except the cucumbers should be covered before the corolla 

 unfolds or immediately after. During the warmer portion of the 

 year the bloom of cucurbits should be protected at least 3 or 4 days 

 before the flower unfolds in order to insure protection. At present 

 many fruits are so covered, but rather indifferently and ineffectually, 

 as proved by an examination of fruits beneath the coverings. Thus 

 during April only 9 out of 43 fruits of the Chinese melon (Morrwr- 

 elica sp.) that had been covered were sound, while at Waipahu on 

 the same date 119 out of 692 young protected watermelons were 

 actually free from infestation. Certain Japanese growers ward off 

 attack by burying the young fruit in the, soil or surrounding it by 

 straw and trash until it is sufficiently old to need no further protec- 

 tion. However, the usual practice among both Japanese and Chinese 

 growers is to place over the developing bud or the recently opened 

 flower a piece of cheesecloth or other fabric. This averages in size 

 about 6 to 7 inches square and is placed lightly over the fruit without 

 any attempt to attach it to the plant, although in certain cases it 

 may be weighted on the edge with earth. The most successful of 

 the protective coverings are those shown in Plate XXIV. In this 

 case the Momordica vines are grown in bushes where the young fruits 

 can be easily found and inclosed in the long case made from news- 

 papers. These cases are left open at the lower end, but are never! 

 entered by the adult flies. 



The protection of fruits by covering with soil, paper, or cloth is 

 a great labor-consuming operation that at present actually protects 

 less than 25 per cent of all fruits covered, except certain Chinese 

 marrows. This method is, however, at present the only one which 

 can be applied with any degree of success, and could be made far] 

 more successful were it applied more intelligently. In a slightly 

 cooler climate a very much higher percentage of fruits could be 

 saved. 



