212 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



In discussion Mr. Busck stated that the ant inhabited aca- 

 cia trees were conspicuously green and uninjured by leaf -eating 

 nsects and stock, because they are so jealously defended by the 

 iants. Cattle and horses have learned not to nibble on the leaves 

 of such trees. One insect however appears to be not only per- 

 mitted to occupy the trees, but seems to be protected by the ants 

 for some reason, namely the wasp Polybia occidentalis, Oliv., 

 which build their curious oblong bell shaped clay-nests in the 

 top of these ant trees and apparently nowhere else. It is signifi- 

 cant that these wasps have no sting, but rely entirely on the 

 efficient ants for the protection of their nests. 



Mr. Busck mentioned in this connection the inter-relations 

 of the birds and the large wasps, which build their nests in the 

 trees occupied by the well known large hanging nests of the social 

 orioles. These wasps sting very severely and aggressively ob- 

 ject to the least interference of man; but the birds hop around 

 the nests and severely shake the branches, without arousing the 

 wasps. The birds in this case have a very formidable protection, 

 from man at least, in these wasps. 



A NEARCTIC SPECIES OF DOLICHURUS. 



BY S. A. ROHWER, 

 Specialist in Forest Hymenoptera, Bureau of Entomology, Washington, D. C. 



The genus Dolichurus is known to ocfcur in the Palaearctic, 

 Ethiopian, Oriental and Neotropical regions, but until recently 

 no species has been discovered in the Nearctic region. The fol- 

 lowing species seems to be quite distinct from all the other 

 species of this genus and adds another genus to the American 

 wasps. 



Dolichurus greenei new species. 



Fem.ale. Length 7.5 mm.; length of the antennae about 5 mm. Cly- 

 peus shining, the anterior margin truncate, the basal middle slightly 

 raised; eyes diverging to the clypeus; face and front opaque, granular, 

 immediately below the anterior ocellus a few shallow, scattered punctures; 

 frontal prominence slightly wider than long, the anterior margin trun- 

 cate; vertex and posterior orbits shining, sparsely punctured; postocellar 

 line somewhat shorter than the ocellocular line; antennae very slightly 

 tapering, the third and fourth joints subequal; pronotum slightly tulx-r- 

 culate posteriorly, medianly with a longitudinal foveolate suture; notauli 



