Morphological Comparisons Between the Obligate Social Parasite, Vespula Austriaca (Panzer), and its Host, Vespula Acadica (Sladen) (Hymenoptera: Vespidae)

Obligate social parasites (inquilines) show a vast array of behavioral and morphological adaptations to their unique mode of life (Wilson 1971). The hazards of colony invasion, usurpation, and subsequent subjugation of members of the host colony (queen and/or workers) require special features in order to overcome colony defenses and to become integrated within the host’s society. Not only do these species have adaptations for colony takeover, but they also lack certain social characteristics, the most notable being the absence of a worker caste. Such traits are exemplified in the workerless ant inquiline, Teleutomvrmex schneideri Kutter, that has enlarged tarsal claws and a gaster with a concave venter which enables this parasite to ride on the dorsum of its host (Wilson 197 l). Among the parasitic bumble bees (Psith’rus spp.) a number of characteristics, such as strong development of the sting and exoskeleton, are adapted for successful colony takeover, while other social traits, such as a pollencollecting apparatus on the hind leg, are lacking (Alford 1975). Similarly, vespine inquilines are distinct from their hosts in possessing stronger exoskeletons, a closer fitting of their abdominal segments, stouter and more recurved stings, broader heads, more powerfully built mandibles, and sharp bidentate clypei (Weyrauch