106 BULLETIN 536, U. S, DEPARTMENT OF AGRICULTURE. 



ing is properly done this remedy is applicable under town conditions, 

 even where the summer rainfall may be heavy. 



In Western Australia Newman carried on spraying experiments 

 during a 5^-months period (December 5, 1913, to May 25, 1914) 

 when the fruit fly was most destructive. From the orchard at 

 Crawly Park, in which he experimented, little or no sound fruit, 

 other than grapes, had been picked for several years. The extreme 

 dryness of the Western Australia summer, during which little or no 

 rain or dew falls, affords an especially opportune time for making 

 the best use of poison sprays. Newman estimated the cost of spray- 

 ing an acre, where an application of one pint of spray was made 

 every 12 to 14 days, to be from $1.50 to $2 per fortnight, and stated 

 that this sum was a mere bagatelle to the loss of fruit during a similar 

 period over a like area. His work convinced Newman that good 

 results will follow the consistent application of poison sprays, par- 

 ticularly when supplemented by the proper destruction of infested 

 fruits. 



In the Hawaiian Islarfds there are no real orchards in which 

 spraying experiments can be conducted under commercial conditions. 

 Severin states that while he captured in 10 kerosene traps, hung 

 among 400 trees, 10,239 flies during a 5-weeks period before starting 

 spraying work, in the following 5 weeks, during which these trees 

 were sprayed about once a week, the same traps caught only 182 

 flies, and of these 93 were caught during the first 6 days after the 

 first application of spray. Inasmuch as the orchard in question is 

 composed of small citrus trees interplanted with peach and con- 

 tains a few strawberry-guava, fig, Chinese-orange and rose-apple 

 trees, and is surrounded on one side by wild guava scrub, it is unfor- 

 tunate that no data were given on the time of the year the spraying 

 was done or on the condition of the host fruits in and about so 

 small an orchard. 



The conclusions of Weinland following his spraying experiments 

 conducted during 1912 in dooryards of Honolulu are misleading. 

 He used the data from 7 traps as a basis for his favorable report; 

 had he used the data from 10 other traps in the same series of his 

 experiments which are on file with the Hawaiian Board of Agri- 

 culture and Forestry he could have shown that on the whole his 

 experiments were not successful, and that in several instances he 

 caught more flies after spraying than before. The writers have 

 demonstrated from an immense amount of data on the number of 

 flies caught in single traps throughout a given year that even when 

 no spraying is done there may be a sufficient falling off in the num- 

 bers of fruit flies captured to mislead one into thinking that the 

 trees had been sprayed. 



