HYMENOPTERA 971 



Tribe BEMBICINI 



With these wasps the ocelli are distorted, the middle tibiae are 

 armed with only one evident apical spur; and the labrum is elongate, 

 pointed, rostriform (Fig. 1210). 



Our best -known representatives of this tribe belong to the genus 

 Bemhix; these are stout-bodied wasps, usually black with greenish 

 or greenish-yellow bands. They burrow in the 

 sand and provision their nests with flies. Some 

 species at least practise progressive provisioning. 

 After excavating its burrow and making a cell, 

 the wasp captures a fly and stings it to death, 

 then places it on the floor of the cell and attaches 

 an egg to it. After the larva has hatched, the 

 mother collects flies from day to day, feeding the 

 larva till it is ready to change to a pupa, closing Fig- 1210.— Faceof 

 the nest behind her each time she leaves it. Bembex: I, lab- 



A common and well-known member of this 

 tribe in the South is Sticta Carolina, which is called 

 the "horse guard." This is a large species which hunts about horses 

 in order to capture flies. 



Microhembex monodonta is one of the most abundant of wasps 

 along the seashore everywhere on the Atlantic, Gulf, and Pacific 

 coasts. This species is black with greenish-white markings; the 

 pleuras and mesoscutum are black and the wings are slightly dusky. 



The North American Bembicini were monographed by Parker 

 ('17). 



Subfamily CRABRONIN^ 



This subfamily differs from all other Sphecidse except the Try- 

 poxylonini in having only one submarginal cell (Fig. 121 1), and it 



Fig. 121 1. — Wings of Crahro singularis; ap, appendiculate cell. 



differs from the Trypoxylonini in that the inner margin of the eyes is 

 not emarginate. It includes two tribes, each of which is classed as 

 a subfamily by some writers. 



