Does a yellow jacket allergy mean a wasp allergy?

Hornet allergy: Yellow jackets are actually hornets. Hornets are close relatives of wasps. Many, if not most, persons allergic to yellow jackets are also allergic to wasps because their venoms have many proteins and allergens in common. Many allergists when making a diagnosis of yellow jacket allergy will treat the patient with injections consisting of yellow jacket, yellow hornet and wasp venoms.

Not necessarily: Yellow jackets are more closely related to the white faced and yellow faced hornets. However there is significant cross reactivity between yellow jackets and wasps and it takes sophisticated tested to determine whether this is clinically relevant.