Bembidion Distribution 



147 



the water's edge B. nigrum (Cobb's Branch) and B. honestum (Sandy 

 River) were extremely abundant. The sandbars were at the time devoid 

 of vegetation and were exposed to full sun at one place and afternoon 

 insolation at the other. Both streams were about 2 to 3 m wide and 

 entrenched in sandy floodplain at both sites. 



Dr. Barr informed me (in litt.) that his specimen from Horse Cove 

 was likewise found on a sandbar, near the mouth of Blackrock Creek, 

 and that repeated visits during the summer of 1969 failed to produce 

 another. This observation parallels my own lack of success at Cobb's 

 Branch after mid-July. Perhaps the species is active as an adult only 

 during spring and early summer, at least in the south. Manee's capture 

 at Southern Pines, North Carolina, was made in April. Lindroth's 

 Ontario specimen was found June 7, 1956. By late July the sandbars at 

 the two Virginia sites were considerably grown up in rank weedy vegeta- 

 tion that considerably altered the former appearance and doubtless also 

 affected the microhabitat conditions as well. 



Examination of my material revealed an interesting structural fea- 

 ture perhaps diagnostic of this species. As shown by Figure 1 the 1st 

 elytral interval (sutural) is provided with one or two adventitious setae 

 near the apical end, in all four specimens. Dr. Newton kindly examined 

 the male holotype at Harvard and reported one such seta on each side, 



Fig. 1. Posterior end of abdomen of specimen of Bembidion plagiatum (Henry 

 County, Virginia) showing accessory setae on 1st elytral intervals apparently 

 characteristic of this species. 



