8O ENTOMOLOGICAL NEWS [Feb., '15 



tween the two jars. A similar experiment was conducted with 

 wet sand which had been previously sterilized. The puparia 

 in both experiments were arranged in a circle close to the 

 wall of the jars so that when the flies emerged and burrowed 

 through the sand their paths might be seen. When the melon 

 rlies emerged, many would bore up to the regions where the 

 jars came in contact with one another and then escaped 

 through the small spaces between the jars. These small 

 spaces were due to particles of sand which rested on the rims 

 of the jars. One could scarcely believe that these large flies 

 were able to flatten their bodies to such an extent as to squeeze 

 through such small spaces as existed between the jars. 



It was evident that some of the melon flies were not able to 

 burrow as far as others, for many died at the upper end of the 

 channels before obtaining their liberty. (See figure.) Flies 

 would frequently bore into an excavation made by other speci- 

 mens, and if the union of the channels would form a circular 

 path, some of the individuals would continue to burrow slowly 

 round and round, and finally die in this endless passage. Usu- 

 ally, however, most of the flies showed a definite orientation 

 and bored more or less directly upward. This negative reaction 

 to gravity is common with many insects after emerging from 

 the egg or pupa. 



As there w r as a possibility that the flies might have been 

 hindered by being against the glass, holes two, three and four 

 feet deep were drilled in hard soil with a fence-post borer. At 

 the bottom of these holes from 100 to 1000 Mediterranean fruit 

 fly or melon fly puparia were placed. The puparia were then 

 covered with sterilized dry or wet sand or soil. After these 

 pits were filled each hole was covered at the surface with a 

 large, mouthed jar which rested tightly against the solid earth. 

 The following table shows the number of Mediterranean fruit 

 flies and melon flies which succeeded in boring through two, 

 three and four feet of sand or soil : 



