14 
Psyche 
[March 
ASILIDS FEEDING ON BUMBLEBEES IN 
NEW ENGLAND 
By Stanley W. Bromley 
In Dr. 0. E. Plath’s excellent book on Bumblebees (“Bum- 
blebees and Their Ways”, Macmillan Company, New York 
City, 1934) he records two instances (p. 62) of bumblebees 
captured by Robber flies. In both cases the large bumblebee- 
like Bombomima ( Dasyllis ) grossa (Fabr.) was the captor. 
As I have collected a number of records of Robber flies prey- 
ing on bumblebees, it might be of interest to present a sum- 
mary of these records. Five different species of Asilids 
were observed to kill bumblebees in New England with a 
total of 76 bumblebees 1 recorded as prey. The dates of cap- 
ture range from 1910 to 1922 and were confined to Southern 
New England, most of them from Massachusetts. 
Asilid Bumblebee Prey Records 
Proctacanthus philadelphicus Macq. 30 
Diogmites (Deromyia) umbrinus Loew 29 
Proctacanthus rufus Williston 10 
Promachus fitchii Osten Sacken 6 
Bombomima (Dasyllis) grossa (Fabr.) 1 
On page 63, Dr. Plath states that he has never seen the 
near relative of B. grossa , B. thoracica (Fabr.) , attack bum- 
blebees, although he believes it probable that this species 
may do so. Thoracica is in general much more common in 
Southern New England than grossa, but I have never seen 
it feeding on bumblebees either, although I have on several 
occasions seen thoracica strike bumblebees in flight and 
unsuccessfully grapple them, indicating that the spirit at 
least is willing. 
1 The bumblebees herein referred to as prey of Asilids in New Eng- 
land were all workers and males of the following species listed in or- 
der of frequency: Bombus vagans F. Sm., B. impatiens Cress., B. per- 
plexus Cress., B. affinis Cress., B. fervidus (Fab.), B. terricola Kby., 
and B. bimaculatus Cress. Some of these were recorded in my papers 
on Asilid Prey, Psyche XXI, No. 6, pp. 192-198 (1914) and Psyche 
XXX, No. 2, pp. 41-45 (1923). 
