ORDER HTMENOPTERA. 175 



Family Mimesidae. Abdomen petiolute, the petiole flattened and 

 usually furrowed above; antenme clavate; middle tibiae with but 

 one apical spur. Mimesa cressonii Pack. ; Psen leucopus Say. 



Family Mellinidae -This group is represented by a single genus, 

 in which the abdomen is petiolate; the head cubical, front very 

 broad, eyes indented; and the first sub-marginal cell receives a re- 

 current vein. Mellinus bimaculatus Say. 



Family Pemphredonidae. Wood-wasps, in which the anterior wings 

 have two complete submarginal cells; prothorax short, transverse; 

 metathorax short, rounded posteriorly; clypeus not cariuate or 

 beak-like. /Stigmas f rater nus Say mines the stems of the Syringa; 

 Cemonus inornatus Harris burrows in the elder; Passalcecm mandi- 

 bularis Cresson burrows in company with the two preceding species. 



Family Crabronidae. These wood-wasps are easily recognized by 

 their cubical heads; short and wide clypeus; and by having but one 

 submarginal and two discoidal cells. The habits of the species are 

 extremely interesting. Crabro sex-maculatus Say mines decaying 

 wood, and C. singular-is Smith bores in posts. In the males of 

 Thyreopus the fore legs have shield-like expansions which are either 

 striped or dotted with black. Rhopahim pedicellatum Pack, bores 

 into the stems of the rose, Corcorus, Spiraea, etc. 



The section or super-family Diplopteryga, corresponding 

 to the Vespidae of early authors, comprises the true wasps, 

 in which the wings when at rest are folded lengthwise. The 

 prothorax reaches back to the base of the wings, the eyes are 

 kidney-shaped, and the legs are smooth, not spiny or bristled. 



Family Masaridae. Antennae clubbed at tip. Masaris vespoides Ores. 



Family Eumenidae. In this and the next family the antennae are 

 filiform. Middle tibiae with one spur at apex; tarsal claws one- 

 toothed; solitary; no workers. The solitary wasps are represented 

 by the genera Eumenes, Odynems, etc. Eumenes fraterna Say con- 

 structs a round cell of pellets of mud, as big as a cherry, which it 

 fills with small caterpillars; Odynerus albophaleratus Saussure also 

 preys on small caterpillars, which it stores in round mud-cells. 



Family Vespidae. In the social or paper wasps, the republic is a 

 numerous one, there being many 

 workers. They all have two spurs 

 at the end of the middle tibiae. Pc- 

 listes americanus Fabr. and other 

 species build nests consisting of 

 few cells in one row, attached 

 mouth downward to bushes. The 

 species of Vespa build several tiers 

 of cells, arranged mouth down- 

 ward, and enveloped by a wall of 

 several thicknesses of paper. Our 

 commoner species are Vespa arena- 

 ria Fabr. and a larger species, the FlG ' ^-~ Ves P a maculata. Nat. size, 

 white-faced wasp, Vespa maculata Linn. The females found the 

 colony, and raise a brood of workers, which early in the summer 

 assist the queen in completing the nest. 



