THE BEHAVIOR OF CERTAIN SOLITARY BEES 369 



fortunate as to see the beginning of one of these performances, 

 but they have continued for thirty seconds to a minute after 

 discovery. 



At first we thought it was a mating performance, but later 

 we found a pair in actual copulo, sitting quietly on the ground, 

 the male surmounting the female with the abdomen curled 

 underneath hers to effect the union. The duration of this 

 mating was perhaps five minutes. But what the significance 

 of this whirligig struggle may be we have not yet determined. 

 At the conclusion of the performance they have always sepa- 

 rated and instantly darted away with a buzz, so we have failed 

 even to determine the sex of the performers. Is it a friendly 

 or an antagonistic encounter, a sexual or merely social or pla- 

 tonic frolic' There may be some of the elements of courtship 

 about it, but so far as we have seen it does not immediately 

 precede or follow mating. 



Megachile brevis Say. 



We were plodding along the railroad track one hot, mid- 

 July day, hunting for ground-wasps, when a little creature 

 emerged from a crack in a tie at our feet and darted away on 

 the wing. It was a little leaf-cutter bee, Megachile brevis Say. 

 After one or two minutes we spied it returning, coming up the 

 track from the east; it located its particular crevice without the 

 least difficulty, entered, reappeared after a few moments and 

 went off directly down the track to the east again. Soon she 

 returned, coming straight along the track as before, and entered 

 her hole without displaying the least confusion. This time she 

 remained in for five minutes, and even a heavy train passing 

 on the parallel track and shaking the earth perceptibly did 

 not alarm her away. 



When next she emerged she sailed directly west, with a dash. 

 She flew with a characteristic gait, neither gliding nor zig-zag, 

 but a combination of the two, like a boy on skates making a 

 smooth, gliding stroke, first with one foot and then the other. 

 She flew about twelve or fifteen inches above the ground, and 

 kept pretty accurately to the same level. After ten minutes 

 she reappeared, coming down the track between the rails, car- 

 rying her bit of green leaf, about one-half inch long. This time 



