796 
Journal of Agricultural Research 
Vol. V, No. 17 
these hatched were laid directly into the pulp along the crack in the peel. 
Of the punctures found in the peel of the cracked fruits, only one con¬ 
tained eggs, and these were dead and shriveled. Mr. Bridwell kept no 
definite record of the number of adult flies reared, but it was large. He 
estimates that from the Popoulu and the Moa fruits he reared about 350 
adults. The thoroughness with which the larvae destroyed the pulp of 
the Moa banana is shown in Plate LIX, figure 2. 
Special attention should be called to the fact that infestation of the 
pulp in these two varieties occurred only in the fully ripe and yellow 
fruits of the Popoulu variety, which has a very thin skin, and in the fruits 
of the Moa variety, the peel of which was cracked, thus removing from 
the exposed pulp beneath the natural barrier to infestation referred to 
below. The ordinary cooking bananas, such as are in general use in the 
islands, are quite unlike the Popoulu and Moa varieties in shape. 
EXPERIMENTS TO FORCE INFESTATION 
While infestation of Hawaiian bananas ha.s never been known to occur 
among fruits grown and harvested in accordance with trade requirements 
and prepared for shipment in accordance with the regulations of the 
Federal Horticultural Board, experiments have been carried on under 
more or less artificial and abnormal conditions for the purpose of deter¬ 
mining whether the general immunity of commercially grown bananas 
in Hawaii is due to the presence of other host fruits for which the fruit 
fly has a greater preference or to some characteristic which renders them 
actually immune. Such experiments have been completed both in the 
field and in the laboratory. 
EXPERIMENTS IN THE FlEED 
As the writers have found that in the field they can bring about an 
infestation of ripe bananas, or in the laboratory of green but well-grown 
bananas that have been cut from the tree so long that the protecting sap 
has ceased to flow to any extent, their field experiments have been con¬ 
fined mainly to forcing, if possible, an infestation of bananas still attached 
to the tree yet sufficiently mature for the export trade. 
During March, 1913, a rearing cage, 9 by 15 by 24 feet, was built over 20 
Chinese banana trees bearing 14 bunches of bananas. Into this cheese¬ 
cloth-covered cage (PI. LXII, fig. 1,2) were introduced from time to time 
a total of over 3,000 Mediterranean fruit flies. The foliage within the 
cage was sprayed every few days with a solution of pineapple juice and 
water, as there was nothing else upon which the fruit flies could feed. 
As the fruits on the various bunches ripened, they were cut and placed in 
rearing jars in the insectary. The 14 bunches represented approximately 
1,000 fruits, which ripened over a period extending from the middle of 
March to June 28. No adult flies developed from any of this fruit. 
In order more closely to confine gravid females with bananas ripe 
enough for shipment, a fine wire cylinder, 20 inches in diameter and 
