One last post on wasps, while I’m still on the topic.

Bees and spheciform wasps, forming the superfamily Apoidea, are hugely diverse in form, size, color, and habits. The rich variety within Apoidea can make the group difficult to recognize, but most share one particular morphological trait that, with practice, can reliably be used to diagnose these insects from other types of wasps.


(Adapted from Scott & Stojanovich “Stinging Hymenoptera, Pictoral Key To Some Common United States Families”, via the CDC)

The pronotum is the first big dorsal plate on an insect’s thorax, and in apoids this plate ends at the sides in a distinctly rounded lobe that does not touch the tegula, a small plate associated with the wing base. Bees, crabronids, sphecids, ampulicids, and other spheciforms have this distinctive pronotal lobe; similarly sized and colored wasps in the Vespoidea do not.


Hylaeus, a bee, has the rounded pronotal lobe.


Can you spot the lobe in this cicada killer wasp?

In contrast, here is Euodynerus, a vespoid wasp showing the non-apoid pronotum without the distinctive lobe:


In vespoid wasps, the pronotum typically touches the tegula in a sharp angle.