Heriades, Spinola, 1808

Rozen, Jerome G. & Praz, Christophe J., 2016, Mature Larvae and Nesting Biologies of Bees Currently Assigned to the Osmiini (Apoidea: Megachilidae), American Museum Novitates 2016 (3864), pp. 1-48 : 38-39

HERIADES (H.) TRUNCORUM (LINNAEUS)

Most nests examined by J.G.R. and C.J.P. were in trap nests (fig. 54), and four of them were each 4.0 cm long and circular in cross section with a diameter of 4.0 mm. Cell partitions and nest closure were uniformly constructed with clear yellowish resin (fig. 55), which on hardening was quite brittle but easily chipped with forceps, suggesting that emerging bees could easily remove partitions and next closures with their mandibles. Cells were arranged in linear series occasionally with empty spaces between, and always with a more or less elongate space between the last cell built and the nest entrance. This tunnel was sometimes empty and other times partly filled with resin (fig. 54). Several cells of a nest in a section of bamboo were also recovered. These cells were 7.5 cm from the nest entrance stoppered by a large amount of resin, but the tunnel itself was completely resin free although the rear of the nest was a 4 mm long cylinder of solid resin. Feces (figs. 54, 55) in all nests tended to be pellets of various shades of orange, from light to dark, which seemed to be mostly exterior to the cocoon fabric and only loosely fastened to the cocoon with threads of silk. Cocoon structure was not closely examined, but did not seem unlike those of Chelostoma or Hoplitis in that at the front end it bore a dense, white air-exchange portal (fig. 55) and SEM scans of the inner surface at the front end revealed the screened openings surrounded by smooth silk (figs. 56, 57).

Nest closures observed by J.G.R. and C.J.P. were flush with the exposed surface and were not implanted with pebbles or other debris as reported by Westrich (1989) and as discussed recently by Rozen et al. (2015).

The rest of the information correlates well with the nest descriptions provided by Westrich (1989). Both he and Müller et al. (1997) pointed out that this species also nests in vacated beetle burrows in old wood and in stems of such plants as blackberries. They also noted that cells were arranged in linear series separated by septa of resin, sometimes with empty chambers between cells. Nest closures were also made of resin in which were implants of pebbles, wood fiber, or other debris.