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Division ACULEATA 



By Karl V. Krombein 



This divisional name is retained because of the substantial biological literature published on 

 the groups of Hymenoptera popularly called ants, wasps and bees. No clear-cut unambiguous 

 criteria exist by which one can separate Aculeata from Parasitica for there are annectent forms 

 in both divisions. 



In North America we recognize about equal numbers of valid species-level taxa in the Acu- 

 leata and Parasitica (or Terebrantia). However, there are comparatively few undescribed Acu- 

 leata, and subsequent revisionary studies probably will synonymize nearly as many taxa now 

 considered to be valid as there will be new taxa described. Undoubtedly there are numerous un- 

 described small Parasitica. 



Aculeata occur in all major zoogeographic regions and on many of the oceanic islands; they are 

 absent from Antarctica. Brothers (1975) recognizes 38 families of Aculeata. The majority occur 

 in America north of Mexico except the Plumariidae, Scolebythidae, Loboscelidiidae and Fide- 

 liidae (sometimes placed in Megachilidae), all small families with very few species. The Cleptidae 

 are here considered to be a subfamily of Chrysididae. The exotic Loboscelidiidae are best con- 

 sidered as an extremely aberrant subfamily of Chrysididae allied to the Amiseginae. Brothers 

 considered the Crabronidae, here treated as a family, to be a subfamily of Larridae. 



Brothers recognized only three superfamilies of Aculeata, placing the scolioid, pompiloid and 

 vespoid families in the Vespoidea, and consolidating the Sphecoidea and Apoidea under the 

 former name. Further discussion of Brothers' arrangement will be found under appropriate su- 

 perfamily headings. 



In general the Hymenoptera included in the Aculeata are characterized by conversion of the 

 ovipositor to a stinging function only. The eggs are no longer exserted through the ovipositor as 

 in most Parasitica but through an orifice anterior to it. The ovipositor with associated poison 

 glands now serves several purposes, the temporary or permanent paralysis of the prey of wasps, 

 as a defensive mechanism in bees and some ants, and as an offensive mechanism in some ants. 

 However, annectent forms occur in some Proctotrupoidea of the Parasitica, and Bethyloidea and 

 Scolioidea of the Aculeata. In many higher Parasitica the wing venation and thorax are much 

 more reduced than in the Aculeata. 



Biologically the majority of Aculeata may be distinguished by their non-parasitic habits and 

 the construction of nests for their young. Most higher wasps belonging to the Vespoidea, Pompi- 

 loidea and Sphecoidea are predaceous upon other arthropods and build nests which vary from 

 simple to quite elaborate. A few species of Pompiloidea and Sphecoidea behave as parasitoids, 

 paralyzing the prey, laying an egg upon it, and making no nest; the prey later recovers and leads 

 a normal life until killed by the growing larva. Most of the vespoid Masaridae and all of the 

 free-living bees have converted to a larval diet of pollen and nectar. Cleptoparasites or 

 brood-parasites, whose larvae develop in the nests of other wasps or bees, have evolved inde- 



