The order Hymenoptera ( Latin for "membrane wing") is a vast assemblage of insects second only to Coleoptera (Beetles) in the number of described species. Hymenoptera species number some 115,000. Of the 6,000-7,000 new species of insects described annually, Hymenoptera is a large component, especially in the parasitic wasp groups. Nearly all commonly encountered Hymenoptera can be recognized by a narrow "waist." When winged, the wings form two pairs that can be held together as a unit, with hooks called hamuli.

cirrusimage.com/hymenoptera.htm