Unknown. The females of H. tenuispina possess a specialized pilosity on clypeus and frons composed of apically twisted bristles (A. Müller, unpublished). Similar facial combs occur in several unrelated bee taxa where they serve to remove pollen from the nototribic anthers of Lamiaceae and Antirrhineae (Houston, 2000; Müller, 1996; Thorp, 2000). Thus, flowers of the Lamiaceae may be important pollen sources for H. tenuispina.