The Sphegoidea of Nebraska 73 
Genus Rhopalum Kirby 
Rhopalum decorus (Fox). 
1895. Crabro decorus Fox, Transactions of the American Entomolog- 
ical Society, xxii, p. 200. 
A tiny black wasp, about 5 mm. in length, easily recognized 
by the petioliform first abdominal segment, which is nodose at 
apex ; intermediate and anterior legs almost entirely yellow, also 
scape of antennae; mandibles whitish, brown apically. Five spec- 
imens were taken at Glen, August 13 (H. S. Smith). These 
were nesting in a clay butte. 
Genus Crabro Fabricius 
SYNOPSIS OF THE SPECIES 
Mesopleura without a distinct ridge, carina or crest (rarely with a 
small, pointed tubercle) before the middle coxae; antennae in the 
male thirteen-jointed; metathorax often smooth, shining......... 1 
Mesopleura with a distinct ridge, carina or crest before the middle 
coxae; antennae in both sexes twelve-jointed; metathorax never 
SMICGeHe aihit HCOATSClys SCM LPLUGOG a (os « Deine aisiscareik sheets becn aad enh aes 18 
1. Ocelli arranged in an equilateral triangle, or nearly, the lateral ocelli 
about as far apart as from the front ocellus; abdomen 
Vaddaresnls aicelll Conyigsinntehil <itak occ el Mere ens Het eeee Sr eae eer einys Gui 2 
1. Ocelli arranged in an obtuse triangle, the lateral ocelli being about 
twice as tar apart as irom: the tront- ocellus....:.00.-Wen a 5 
2. Recurrent nervure in front wings received by the cubital cell 
far beyond the middle; abdomen red, black apically; tem- 
ples: produced, intosa. toath: below... hu. 6. ess caw ene viereckt 
2. Recurrent nervure in front wings received by the cubital cell 
at or about the middle; abdomen entirely black; temples 
Batre; EMO ER Gels wire OMe 5 Srna, oases lank aie ayieie tas tava, Shed See 3 
3. Scutellum black; intermediate tibiae yellow on basal portions only, 
ImCavuUs 
3. Scutellum entirely yellow; intermediate tibiae entirely yellow on 
Olitery SiG eee ame ercpr ates eateeesnete ois Gack asete abe e eek occa eee eee a 
4, Abdomen somewhat longer than head and thorax united, 
the first segment not broad and narrowed basally; length 
GPU. Roe eee ai aaa SUS ow ae eas Te ee ee scutellifer 
4. Abdomen a little shorter than head and thorax united, the 
first segment broad; length 4.5-5 mm.................. lentus 
Ee. tl Cea see ees SR gee OAD a Og AAR Mires featier as i it, 6 
SEN PPL la Te taicin al AO ea oa CRP aLAS DE, ohepie wl Renate Saree: a a ee 12 
6. Anterior legs abnormally developed, with a shield-like ex- 
Patiston on gies TIMMS vc. IES eas Rae ante Oe ee eee 7 
395 
