MEDITERRANEAN FRUIT FLY IN HAWAII. 



107 



The only test of poison sprays made by the writers was in an 

 attempt to control the Mediterranean fruit fly under adverse town con- 

 ditions such as have been described on page 11. The city block in 

 Honolulu bounded by Punahou, Beretania, Wilder, and Makiki 

 Streets was sprayed every 2 or 3 days from July 17 to August 28, 

 1913. The adjoining blocks to the southeast were held as a check 

 and the number of flies captured in 145 traps in the sprayed area 

 and in 147 traps in the check area constituted the basis for deter- 

 mining the benefits of the poison spray. Knapsack sprayers only 

 were used, and while all trees and shrubs received spray, none were 

 sprayed more than 9 feet above ground. The average number of 

 flies caught daily each week is. recorded in Table XXIX. 



Table XXIX. — Number of Mediterranean fruit flies caught in 145 and 147 traps hung 

 in sprayed and unsprayed areas, respectively; spraying begun July 17, ended Aug. 28, 

 1913. 



Date. 



July 5. . 

 July 12. 

 July 19. 

 July 26. 

 Aug. 2. 

 Aug. 9. 

 Aug. 16 



Average number of 

 flies caught each day 

 during week ending. 



Sprayed 

 area. 



1,191 

 881.4 

 936 

 541.2 

 472.5 

 383.8 

 269.4 



Unsprayed 

 area. 



769.2 



722.5 



769.4 



727.2 



904.5 



937 



762.8 



Date. 



Aug. 23 . 

 Aug. 30. 

 Sept. 6. 

 Sept. 13 

 Sept. 20 

 Sept. 27 



Average number of 

 flies caught each day 

 during week ending. 



Sprayed 

 area. 



215.8 

 111.1 

 102.7 

 71.2 

 76.5 

 90 



Unsprayed 

 area. 



561.8 



439 



315.5 



219.1 



151.8 



141.2 



The data show that the number of flies caught in the sprayed area 

 was greatly reduced by the spraying. The reduction in flies was not 

 great enough, however, to save fruit of any host ripening from becom- 

 ing badly infested. Similar experiments conducted during May and 

 June, 1914, in an attempt to protect peaches ripening in town door- 

 yards were failures. Of several thousand fruits only three reached 

 maturity uninfested. 



The composition of the poisoned-bait spray used against the Mediter- 

 ranean fruit fly consists of some poison, a sweet substance attractive 

 to the adults, and water. Mally in 1909 used the following formula: 

 Sugar, 3 pounds; arsenate of lead, 4 ounces; water, 5 gallons. He 

 found that from 1 to 1 J pints were sufficient for the average 10-year- 

 old peach or nectarine tree. Lounsbury in his town demonstration 

 work used a spray consisting of 6 pounds brown sugar, 6 ounces 

 arsenate of lead paste, and 8 gallons water. Weinland used a spray 

 of 3| pounds lead arsenate paste, 10 pounds brown sugar, 5 gallons 

 plantation molasses, and 50 gallons water. Severin used the Mally 

 formula, but increased the lead arsenate from 3 to 5 ounces. The 

 writers used the formula of Weinland. 



