18 
BULLETIN 640, U. S. DEPARTMENT OF AGRICULTURE. 
while still hard, though mature, and allowed to soften in storage. 
With most varieties it is not until the fruits are mature enough for 
gathering or dropping that adults lay eggs in them. Many fruits 
upon the market are not in the least affected. While avocadoes are 
not usually a favorite host for the fly, they are sufficiently infested 
to warrant the quarantine prohibiting the shipment of them to the 
mainland. (See fig. 13.) 
BANANAS. 
Experimentation during the past four years in Hawaii has proved 
that the Chinese banana 1 and the Bluefields banana 2 are prac- 
tically immune from attack if harvested and shipped to the coast in 
accordance with the demands of the trade and the Federal Horti- 
Fig. 16.— Loss to coffee-mill owners due to infestation of coffee cherries by Mediterranean fruit fly. 
Coffee beans to left pulped from uninfested cherries; beans to right pulped from infested cherries. 
Cherries failing to pulp, because infested, appear as black; pulped beans are grayish white. (Orig- 
inal.) 
cultural Board. Persons wishing the results of careful experimental 
work used as a basis for these conclusions may obtain them in 
printed form by applying to the Bureau of Entomology. The 
immunity of commercial varieties of bananas has been shown to be 
due to the fact that neither the eggs nor the newly-hatched larvae 
can survive in the tannin-laden peel of the green though mature fruit. 
Indeed, the copious and sudden flow of sap from egg punctures' made 
by the female fly in unripe bananas renders the successful placing of 
eggs in such fruits difficult and rare. 
No fruits of the Chinese variety ripening prematurely on bunches 
in plantations have been found infested. But of the cooking bananas, 
flies have been reared from the ripe and yellowish fruits of the thin- 
skinned Popoulu variety (fig. 14) growing in the field, and from the 
1 Musa cavendishii. 
- Musa sapientum. 
