1942] 
Bee-killing Asilidce 
83 
decline in the utilization of grass for hay and the abandonment 
of mowing in many parts of New England as a result of the 
displacement of the horse by motor driven vehicles. 
Promachus fitchii tends to disappear from hayfields after 
they have been abandoned and an old-field succession of vary- 
ing stages from grasses to shrubs and trees takes place. So 
after all, the species begins to lose any significance it might 
have had as a bee-killer thirty years ago, with the changing 
times and conditions of more recent years. 
