Cuckoo Yellowjacket

This wasp is an obligate social parasite. As a result, it possess special morphological adaptations to take over host colonies. These adaptations include larger body parts such as a larger head width than its host V. acadica. As an adaptation to its parasitic lifestyle, V. infernalis has a large, heavily curved stinger; this curving allows the parasitic wasp to puncture through the intersegmental membranes of host colony workers who are defending their nests. The male abdomen is longer with thick lateral black bands while the female abdomen is wider with fewer lateral black bands and black dots. V. infernalis wasps have a characteristic black and yellow colouring throughout their bodies. Irregular margins and narrow yellow marks on the scape are often used to identify Vespula infernalis.

Vespula infernalis is found in the Nearctic region, in the Boreal region of North America. The species is not considered rare and is stable throughout its range. These wasps are seen throughout all the provinces and territories of Canada and in certain states in the United States; Alaska, New Jersey, Michigan, Wisconsin, North Dakota, New Mexico, Arizona, and California.

V. infernalis parasitises V. acadica. Near the dorsal edge of V. infernalis mandibles, there is a fourth marginal tooth whereas the host, V. acadica has three. When researchers dissected individuals of V. infernalis, they found that they had larger, sturdier mature muscle bundles in abdominal sterna and tergum than the muscles in a queen of V. acadica. As a result, it was more difficult to dissect V. infernalis. Nests of V. acadica were found to be smaller than normal due to the parasitism of V. infernalis.