An Illustrated key to Alfalfa Leafcutter Bees Eutricharaea 
(Hymenoptera: Megachilidae) 
F.D. Parker 
Bee Biology and Systematics Laboratory, Agricultural Research Service, USDA 
Utah State University, Logan, 84322 
The distribution of leafcutter bees Megachile, subgenus 
Eutricharaea, formerly included the continents of the Old World, but 
recently several species have become established in the continental 
United States (Hurd, 1954; Parker et al., 1976). The species in North 
America are associated with leguminous plants, especially alfalfa. 
One, M. pacifica (Panzer), is used commonly for alfalfa pollination; 
another, M. concinna Smith, is used for alfalfa pollination but mostly 
inadvertently by way of trapping populations of wild leafcutter bees 
in southwestern states and then transporting them to seed-growing 
regions in the northwest. Populations of concinna in California are fre¬ 
quently confused with pacifica (one sample of supposed pacifica sent 
to me by a California leafcutter bee dealer was all concinna). 
The following key and illustrations will separate the established 
species in North America, though Hurd (1954) reported another 
species, “M. argentata Fab.” from California. I have not included this 
species because of the taxonomic confusion surrounding the correct 
name and identity. However, it is similar to concinna and is readily 
identified in the male by the median swelling on the apical margin of 
the 4th sternum and the cleft, digit-like paramere. Females of 
“argentata” have two patches of white hair on the last sternum. 
I have not attempted to record the present distribution of these 
species because of the constant mixing of leafcutter bee populations 
from many areas via the “bee-board” traffic. 
Key to the North American Eutricharaea 
Males 
1. Foveae on tergum 2 oval, distinct (Figs. 1, 2). Hair fringe on front 
tarsi short not more than width of basitarsus (Fig. 4), gena 
behind mandibular base round.2 
Foveae on tergum 2 indistinct, indicated by short hair only; hair 
fringe on front tarsi longer than width of basitarsus (Fig. 
3); gena behind mandibular base formed into sharp projec¬ 
tion, points clearly seen in facial view (Fig. 5); apical sterna 
as in Fig. 6. concinna Smith 
2. Foveae present on terga 2 and 3 (Fig.2); apical sterna as in Fig. 8 
. apicalis Spinola 
Foveae absent on tergum 3 (Fig. 1); apical sterna as in Fig. 7 
. pacifica (Panzer) 
The Pan-Pacific Entomologist 54:61-64. January 1978 
