but a few brachypterous (short-winged) and apterous (no wings) species are known.

Spider wasps are best distinguished from vespoid wasps in having (in most species) a transverse groove bisecting the mesopleuron (the mesepisternal sclerite, a region on the side of middle segment of the thorax above the point where the legs join). They have antennae with 10 flagellomeres in females and 11 in males. Most Pompilidae have straight inner eye margins. The hind wings do not have a distinct claval