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



prematurely ripe, cracked, or partially decayed fruits, offer no danger as carriers of 

 the Mediterranean fruit fly, provided they are wrapped and shipped in accordance 

 with the demands of the trade and the Federal regulations. 



In addition to the data already presented by the writers, on the immunity of bananas 

 during a 10-day period after the fruit is sufficiently mature for shipment during the 

 summer months, other experimental work has been carried out by H. F. Willard 

 under the writer's direction. This experimental work in detail emphasizes so well 

 the immunity of well-grown bananas still attached to the tree but green in color, 

 although many fruits on the same bunch have either cracked or ripened, that por- 

 tions of the data are given herewith. The hands of fruit are numbered from the 

 stem end of the bunch. 



On November 30, 1915, 14 bunches of Chinese bananas marked in the field at Moiliili 

 for shipment within two days to California were requisitioned and held uncut for 

 experimental work to determine how long during the winter months the bunches 

 could hang after they were sufficiently ripe for the export trade and still ward off 

 attack. A wire-screen cage containing 300 adult flies was placed over one bunch 

 December 13-15, and three days after its removal an examination of the 131 fruits 

 on the bunch, all green in color, showed 108 fruits to be free from attack. Of 

 those attacked 20, 1, and 1 had respectively, 3, 1, and 4 punctures, all of which con- 

 tained no eggs and were more or less superficial; a single puncture in the remaining 

 fruit contained two living first-stage larvae which later died. 



A second bunch from which there had been cut on December 22 1 sound yellow 

 fruit, on December 27, 2 sound and 2 cracked yellow fruits, and on December 29, 3 

 cracked yellow fruits, was caged on the last date with 300 adults. On December 31, 

 or one month after the fruit was sufficiently ripe for shipment, the cage was removed 

 and on January 3 examined with the following results: 



Hand 1: 13 fruits; 7 green and puncture free. Six yellow, 2 puncture free; 

 1, 1, and 2 had, respectively, 4, 2, and 1 empty punctures. 



Hand 2: 15 fruits; 10 green and puncture free. Five yellow, 2, 1, 1, and 1 

 had 0, 2, 1, and 9 punctures. Punctures empty but ones which con- 

 tained 2 first stage larvae that soon died. 



Hand 3: 15 green puncture-free fruits. 



Hand 4: 14 green fruits; 12 puncture free, 2 had 1 empty puncture each. 



Hand 5: 9 green fruits; 7 puncture free, 2 had 1 empty puncture each. 



Hand 6: 12 green fruits; 11 puncture free, 1 had 1 empty puncture. 



Hand 7: 14 green fruits; 13 puncture free. One fruit had been bruised, so that 

 it was yellow and had begun to decay on one side; it had 7 punctures, of 

 which 2, 2, 1, and 2 contained 6, 1, 4, and eggs, respectively. From this 

 fruit 4 adult flies were reared. 



Hand 8: 7 green fruits; 5 puncture free, 1 with 3 empty punctures, and 1 with 

 1 empty and 3 dead and 1 living first-instar larvae. Living larvae died in 

 puncture. 



A third of the bunches marked November 10 was caged with 300 adults on January 

 5, after 43 yellow bananas had been cut from the bunch. On January 7 the cage was 

 removed and the bunch cut. An examination made on January 11 gave the follow- 

 ing results: 



Hands 1 and 2: Fruits had ripened and been cut before caging. 

 Hand 3: 4 yellow fruits, 3 puncture free. Remaining fruit had 2 punctures 

 with eggs and eggshells. No adults were reared though the fruit was held 

 over sand. 

 Hand 4: 8 yellow fruits, 5 puncture free; 1,1, and 1 fruits had 3,1, and 1 empty 



punctures. 

 Hand 5: 12 yellow fruits, 9 puncture free; 1,1, and 1 had 3, 2, and 1 empty 



punctures, respectively. 

 Hand 6: 13 fruits, 12 green and 1 yellow; no punctures. 

 Hand 7: 12 green fruits, 11 puncture free; 1 had 2 empty punctures. 

 Hand 8: 11 green fruits, 9 puncture free; 2 had 1 empty puncture each. 



