No. 22.] HYMENOPTERA OF CONNECTICUT. 329 



Mesostenidea Viereck. 

 Mesostenus Authors, not Gravenhorst. 

 Type : Mesostenus ligator Gravenhorst. 

 Wings almost clear. 



Key to Species. 



1. Thorax mostly reddish 2 



Thorax mostly or entirely black 3 



2. Thorax mostly reddish, dorsulum, scutel and postscutel not 



reddish; length 6-1 1 mm.; head black, marked with yellow, 

 antennae with a yellow annulus; abdomen reddish, without 

 bands, exserted portion of ovipositor nearly as long as 



abdomen thoracica 



Thorax almost entirely reddish, sutures more or less black; 

 propodeum with a spine on each side, the spine tipped with 

 yellow; face yellow; antennae annulate with yellow ....arvalis 



3. Abdomen more or less reddish above 5 



Abdomen banded with yellow, not reddish 6 



4. Petiole of abdomen, only, reddish; propodeum with yellow 



spots; antennae with a yellowish annulus; length 7 mm.; 

 abdomen banded with yellow; exserted portion of ovipos- 

 itor somewhat shorter than abdomen exapta 



Abdomen above mostly reddish, not banded; thorax almost 

 entirely black; length 9 mm. or nearly 5 



5. Antennas with a yellowish annulus; , exserted portion of ovi- 



positor nearly as long as abdomen americana 



Antennae without an annukis; wings with a rather deep brown 

 tinge (male) prompta 



6. Antennae with a pale annulus 7 



Antennae without a pale annulus; length 7 mm.; hind tibiae 



not annulated with yellow Candida 



7. Length 12 mm.; hind tibiae without a yellowish annulus; ex- 



serted portion of ovipositor shorter than abdomen 8 



Length 10 mm.; hind tibiae with a yellowish annulus; exserted 



portion of ovipositor about half as long as abdomen 



albomaculata 



8. Propodeum with a spinous process on each side; second dor- 



sal abdominal segment with an apical and basal yellow 



band spinaria 



Propodeum with a tubercle on each side of posterior face; 

 second dorsal abdominal segment with a yellow band only 

 at apex fortis 



M, (Polyaenus) spinaria (Brulle). 

 Stonington, 26 August, 1906 (J. A. Hyslop). 

 M. (P.) prompta (Cresson). Possibly the male of 

 spinaria. 



