166 BOULDER REVERIES. 



and fireworks of the Glorious Fourth, so glanc- 

 ing down, I found that I had trodden upon a 

 globular a oak-apple" or gall an inch or more in 

 diameter. It had a tough, air-tight skin or 

 outer wall, and when stepped upon had popped 

 as would a toy balloon or an inflated paper bag. 

 In the center was a minute pea-like ball, from 

 which radiated in every direction scores of 

 slender filaments which were attached to the 

 inner wall of the cover, thus serving like guy 

 ropes to held the "pea" or larval chamber in the 

 exact center of the sphere. On cutting open 

 the central portion there was disclosed the liv- 

 ing pupa of the hymenopterous insect which 

 had formed the gall. It was nearly ready to 

 emerge, the wings and joints of its antennas 

 being plainly visible beneath a hand lens. My 

 footstep had accidentally burst its protective 

 sphere a few days too soon and so prevented its 

 coming forth as a minute, blackish, four- 

 winged fly.* These galls mature in mid-sum- 

 mer, and are usually quite common on the 

 or leaves of the black and red oaks. 



*Amphibolips inanis O. S. 



