1975] 
Barrows — Hylaeus 
75 
characteristic of the halictine. The longitudinal axes of the burrows 
and cells of the nests were horizontal as is typical for nests of L. 
zephyrum in vertical banks (Batra, 1966). Burrows and nest en- 
trances were similar in size to those of L. zephyrum. Thus there is 
no evidence that the Hylaeus did any nest excavation; it appears to 
have merely used available nests for its own purposes. Furthermore 
there is no evidence that the Hylaeus entered occupied Lasioglossum 
nests, although this possibility exists. 
All six Hylaeus nests were discovered after their entrances had 
been closed, each with a sheet of a cellophane-like material flush with 
the surface of the soil bank. The sheets had striarions radiating from 
their centers and small openings along their margins. A female of 
H. bisinuatus was discovered licking across a nest entrance already 
closed by a “cellophane’ ’ sheet. Evidently she was finishing the clos- 
ure. She revolved around the entrance 3 times in 18 minutes while 
she licked 22.5 times per minute (n = 2 min) across the sheet; dur- 
ing this time she took occasional rests of several seconds each. During 
each lick the tip of her proboscis moved from her midventral area 
to a point in front of her head. 
For identification she was captured before she finished the closure 
and two days later (on 5 July) her nest was examined (Fig. 1). All 
three of the cells in her nest were provisioned with a soft yellow 
material, most likely a mixture of pollen and nectar as is used by 
Fig. 1. Top view of a nest of Hylaeus bisinuatus made in a nest of 
Lasioglossum zephyrum; B, main burrow; C, Hylaeus cell inside Lasioglos- 
sum cell; M, cellophane-like membrane secreted by the Hylaeus. 
