Bialba sport feathery
arista with lateral white bands and orbital bristles on the posterior half of the front, as well as a single
vibrissa. The
mesonotum is shiny and dark with six rows of
acrostichal bristles along the top and two pairs of dorsocentral bristles alongside them. The
scutellum is bulbous and a similar color to the mesonotum, with two pairs of
macrochaetae but no
setae. The wings of
Bialba have a weak
anal vein, and the discal and second basal
cells of the wing are
confluent.
B. rotunda is 2.1 mm long with each wing measuring 1.8 mm. Its distinguishing feature is its white frontal bands flowing on to the antennae. The head is orange-tan between these bands, which taper toward the back of the head, leaving small, dark, triangular areas on either side of the head where the orbital bristles are located. The second segment of the antenna is tan along the middle and white on the sides, and the third segment is snowy white. The face is dirty tan. The mesonotum, scutellum,
pleura, and
abdomen are brownish-black with metallic tinges. The
haltere is pale tan, and the legs are brownish and darkest at the
femora. == Distribution and habitat ==