Image Credit: gailhampshire
Hornets (Vespidae) – predators – Hornets, both the solitary and social ones, are insect predators. Hornets are frequent dive-bomb predators upon flower-visiting insects. Vespid hornets can be told from look-alike bees by the shape of their pronotum and the fact that the females do not have pollen-transport devices.
The hornet prothorax is V-shaped (easily seen yellow lines on left-hand and right-hand pictures can fool you because they highlight only the base of the prothorax), extending about halfway along the length of the thorax (see illustrations of yellow-jackets below); the wasp and bee prothorax is a tiny circle at the edge of the main thorax only (see the following set of images).
These are pictures of, respectively, Ancistrocerus, Eumenes, Euodynerus and Stenodynerus – all common genera in Oregon. Eumenes, with the easily observed extra constriction of the abdomen, is typical of many of the genera.