60 THE SOLITARY WASPS. 



minutes the nest is ready and the wasp turns her attention to 

 scattering all the dirt that has been thrown out, sweeping the 

 ground clean so that no sign of her work remains. We have 

 often speculated as to the meaning of the careful and consci- 

 entious performance on this part of her task. With those wasps 

 that nest by themselves it is not easy to see what enemy they 

 are providing against in hiding the entrance to the nest, but the 

 precaution seems still more unnecessary and even absurd in the 

 Bembex field, where there is no possibility of concealing the 

 colony, and where the nests are only an inch or two apart so 

 that an enemy might burrow anywhere with the certainty of 

 finding one. Moreover, the only enemy that we could discover 

 was the parasitic fly which never attempts to enter when the 

 hole is closed. However, unmoved by our opinion on the sub- 

 ject, spinolae spends five or six minutes of her precious time in 

 making the neighborhood of her home quite tidy, and then she 

 fills in the mouth of the nest with a little loose earth before 

 going away to catch her fly. 



Oxybelus, though she is limited in choice by her small size, 

 can catch a fly in three or four minutes. Bembex is strong 

 enough to take anything that she sees, and she has no preference 

 for one species above another, yet she seldom finds one under 

 twenty or twenty-five minutes. When she comes back nothing 

 of the fly is visible unless it is unusually large, so closely is it 

 held under her bodv by the second pair of legs. She alights 

 and scratches away the loose earth at the entrance of the nest 

 with ; her first legs, and then, as she creeps within, she passes the 

 fly along from the second to the third pair, so that the end of 

 its body, projecting beyond the abdomen of the wasp, is visi- 

 ble for an instant before it is carried inside. Sometimes she 

 drops the fly behind her and then, turning around, pulls it in 

 with her mandibles. In other cases, where a longer portion of 

 the tunnel has been filled with earth, the fly is left lying on the 

 ground while the wasp clears the way. This offers a favorable 

 opportunity to parasites, especially as the fly is not placed with 

 any regard to its safety but is dropped anywhere. The dirt that 



