Handbook of Nearctic Chalcidoidea

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Generally 1 mm or more in length; body often metallic or dark in color; metasoma narrowly joined at propodeum (petiole may or may not be apparent); tarsi always 4-segmented; postmarginal vein present or absent.

Generally 1 mm or less in length; body usually pale yellow to white, sometimes with dark markings or wholly dark, but not metallic; metasoma broadly joined to propodeum; postmarginal vein absent; tarsi ususally 3 or 5-segmented (if 4-segmented, than club large and undivided or wing fringed with long setae, or only middle tarsi 4-segmented).