1977] 
Porter — Mesostenines 
49 
1. Ovipositor tip 0.7 as long from nodus to apex as deep at nodus; 
propodeal cristae weakly oblique; first flagellomere 5.0 as 
long as deep at apex; postpetiole 0.83 as wide apically as long 
from spiracle to apex; propodeal punctation definitely sparser 
basad of basal trans-carina; second gastric tergite mat with 
small punctures separated in general by a little more to some- 
what less than their diameters M. opuntiae n. sp. 
Ovipositor tip 1 1.5 as long from nodus to apex as deep at nodus; 
propodeal cristae strongly oblique; first flagellomere 4.2 as 
long as deep at apex; postpetiole 0.95 as wide apically as long 
from spiracle to apex; propodeal punctation hardly sparser 
basad of basal trans-carina; second gastric tergite more shin- 
ing with small punctures separated mostly by about 1.5 their 
diameters M. sicarius Townes. 
FIELD NOTES: Netted in arid Prosopis-Opuntia association. 
SPECIFIC NAME: from the genitive singular of Opuntia. 
14. Mesostenus longicaudis Cresson 
SPECIMENS EXAMINED: 5 females, 7 males: BENTSEN PARK (Net: 
1 female, 12-20 III ’77; Malaise: 1 male, 16-31 V ’76); BOTANICAL 
garden (Net: 1 male, 12-20 III ’77; 2 females, 15 III ’76; 1 female, 
1 IV ’75; 2 males, 27 VIII ’76; 1 female, 3 males, 3-9 IX ’76). 
HABITAT: Herbaceous growth in abandoned orange groves; amid 
pink verbenas on an otherwise well-cut lawn; weedy areas at edge 
of woods; rarely strays into deep woods; flies in full sunlight. 
PHAENOLOGY: Peaks in spring and late summer. Seems absent 
in winter and June-July. Valley records include 4 specimens for 
March, 1 for April, 1 for May, 2 for August, and 4 for September. 
Flies from mid-spring to mid-fall in most of south but does not 
appear before early July in north. 
DISTRIBUTION: Most of U.S. and Mexico. 
Genus Bicristella 
This is the first record of Bicristella from the United States. 
15. Bicristella texana n. sp. 
(Fig. 5) 
Holotype: female, USA (Texas: Hidalgo County, Bentsen Rio 
Grande Valley State Park, 29 XII ’76, C. C. Porter). (Townes). 
