HYMENOPTERA 893 



BB. Antenna with thirteen or fewer segments; hind wing with closed cells; 

 legs each with a single trochanter (aculeate or stinging Hymenoptera). 

 C. Hind corner of pronotum not in the form of a rounded lobe and always 

 extending back to touch the tegula (Fig. 1195, A). 



D. An erect scale or one or two knot-like swellings on the stalk between 

 the main body of the abdomen and the thorax (alitrunk); front wing 



without vein M2 . . . (ants), p. 954 Formicid.^ 



DD. No scale or node between the abdomen and the thorax; front wing 

 with vein M2; antenna usually with twelve segments in the female and 

 thirteen in the male. 

 E. Cell M4 of fore wing longer than cell Cu + Cui (Fig. 1182); wings 



can usually be folded lengthwise, p. 965 Vespid^ 



EE. Cell M4 of fore wing shorter than cell Cu + Cui; wings can not 

 be folded. 



F. Mesopleurum divided by a transverse groove into an upper and a 

 lower half; legs unusually long, the hind femur reaching approxi- 

 mately to the tip of the abdomen, p. 950 P0MPILID.E 



FF. Mesopleurum not divided by a transverse groove; legs shorter. 



G. Hind coxae widely separated by the broad plate-like metaster- 



num which overlaps their bases; apical part of wing membrane 



with fine parallel ridges; eye margin strongly notched opposite 



the antenna, p. 954 Scoliid^ 



GG . Hind coxae not widely separated and not overlapped at the base. 

 H. Antenna with twelve segments (females), p. 953.Tiphiid^ 

 HH. Antenna with thirteen segments (males). 



I. Abdomen without any or with two visible terminal spines. 



p. 953 '. MUTILLID^E 



II. Abdomen with a single upcurved terminal spine, p. 953. 

 TlPHIID^ 



CC. Hind corner of pronotum in the form of a rounded lobe and not touching 

 the tegula (Fig. 1195, B). If the thorax is so hairy that the pronotum is 

 invisible, the specimen is a bee and belongs here. 

 D. First segment of hind tarsus not dilated; hairs not plumose; abdomen 



often petiolate. p. 979 Sphecid^ 



DD. First segment of hind tarsus enlarged and flattened; some of the 

 hairs plumose, especially those on top of the thorax . . . (bees). 

 E. Hind tibia without apical spurs . . . (honey-bee), p. 1005. Apid^ 

 EE. Hind tibia with apical spurs. 



F. Cell below the stigma of fore wing with a hair-like line extending 

 downward from the base of the stigma; anal lobe absent; hind 

 tibia of females and workers with a corbicula except in Psithyrus . . . 



(bumblebees), p. looi Bombid^e 



FF. Cell below the stigma of fore wing without a hair-like line or the 

 hind wing with an anal lobe; hind tibia without a corbicula. 

 G. Tongue short, its apex divided (bifid), p. 993. . . . Prosopid^ 

 GG. Tongue long or short but its apex never divided and fre- 

 quently pointed. 

 H. Front wing with three cells beneath the stigma and the cell 



beyond the stigma, p. 995 Andrenid^ 



HH. Front wing with two cells beneath the stigma and the cell 

 beyond the stigma. 



I. Labrum not large and free, usually entirely concealed by 

 the clypeus, if visible then strongly inflexed; most females 

 with a ventral abdominal pollen-collecting brush; pygidial 

 area absent, p. 999 Megachilid^ 



II. Labrum large, free, and uncovered; female without a 

 ventral abdominal pollen-collecting brush; pygidial area 

 usually present, p. 995 Andrenid^e 



AA. Wings absent or reduced so that they are useless for flight and the normal 

 venation is disturbed. 



B. An erect scale or one or two knot-like swellings on the stalk between the 

 mainbody of the abdomen and the thorax (alitrunk); antenna elbowed . . . 

 (ants), p. 954 FoRMiciD^ 



