464 Journal of Agricultural Research voi.xv, no. s 



PHEIDOLE MEGACEPHALA AS A PREDACIOUS ENEMY OF THE 



FRUIT FLY 



Although several species of ants are common in the Hawaiian Islands, 

 the cosmopolitan ant P/ie«io/e mc^acg^/ia/a Fab ricius greatly outnumbers 

 all others and is enormously abundant throughout the islands at low 

 elevations. It is quite probable that it checks and greatly limits the 

 increase of several of these species. It is quickly drawn to any fresh or 

 decaying animal matter and the soft body of the fruit-fly larva falls an 

 easy prey to it. It has been generally assumed, that this ant destroys 

 large numbers of fruit-fly larvae throughout the year. Very little defi- 

 nite data are on record, however, covering investigations on this rela- 

 tionship. Though the following records are not extensive, they all point 

 in one direction and are significant. 



Four hundred and eighty-eight kamani fruits collected from a certain 

 tree in Honolulu on December 3, 191 6, were spread out under the tree on 

 a large piece of canvas covered with i inch of sand and left for 10 days. 

 By this time practically all of the contained fruit-fly larvae had developed 

 and pupated in the sand beneath the fruits or had been carried away 

 by ants. The sand was then sifted and the fruit-fly puparia were 

 counted. A total of 606 fruit-fly puparia were obtained. This was 

 an average of 1.2 larvae per fruit. During November and December 

 969 more fruits were gathered from the same tree and taken to an 

 ant-proof insectary to be held in boxes of sand for 10 days. From 

 these 4,895 fruit-fly puparia were obtained, or an average of 5 larvae per 

 fruit. Here four times as many larvae per fruit developed in the lot 

 where the ants were excluded. From 1,301 fruits of the same kind col- 

 lected from another tree in Honolulu in November, 191 7, and similarly 

 placed and held for 10 days on canvas under the tree, 3,742 fruit- 

 fly puparia were ultimately obtained. From the same tree and col- 

 lected at approximately the same date, 909 fruits were taken and 

 brought to the ant-proof insectary. Fiom these 10,1 19 fly puparia were 

 secured. Here again almost four times as many larvae per fruit were 

 obtained from the fruits held away from the ants. On January 25, 1918, 

 664 loquats were collected from several trees in a certain yard in Hono- 

 lulu and divided in half, one half going out on the canvas and the other 

 part to the insectary. From the lot on the canvas, after 10 days' 

 exposure, 156 fruit-fly puparia were gathered, and from those in the 

 insectary a total of 840. In this case the ant-proofed lot produced over 

 five times as many puparia. On January 29, February 2, and February 

 6, 1918, an aggregate of 3, 100 fruits of the black myrobalan was collected 

 from one tree. This total was divided in half as soon as each lot had been 

 collected, the two portions being handled as in the above cases. From 

 the fruit held in the insectary 6,668 fly puparia were obtained, while 

 only 4,385 puparia were ultimately secured from the half placed out on 



