About Palpada albifrons (Wiedemann, 1830)
For terms used in this description, refer to the Speight key to genera and glossary, archived January 22, 2023 at the Wayback Machine. Palpada albifrons adults measure 8–9 mm (0.31–0.35 in) in length.
Head: The face is covered with white pollen and thick white pile, which is more abundant and conspicuous on the frontal triangle. The facial stripe and gena are shiny black. The eyes have fine hairs, and males are holoptic. The antennae are faintly reddish or brown, and the arista is bare.
Thorax: The scutum is covered with yellowish-white pile in its front portion, intermixed with blackish pile toward the back. In front of the scutal suture there is a broad, conspicuous grayish pollinose band, and on each side of the scutum there is an oblique spot extending from the wing base backward toward the scutellum. Females of this species differ in having a complete grayish band on the scutum in front of the scutellum. The scutellum is yellow, with a narrowly black base and black pile.
Abdomen: The first abdominal segment is black, with yellow outer angles. The second segment is light yellow, with a narrow median opaque black stripe that does not quite reach the hind margin. This stripe is a little broader at its front end, where it connects to the semicircular black area below the scutellum. The third segment has an oval reddish-yellow spot on each side, which is confluent with the yellow of the preceding segment. The hind border of the third segment is yellow, and the black area is deep opaque with no shiny spot or band. The fourth segment has a yellow hind border, and a narrow, interrupted shiny fascia that is dilated on the sides. The hypopygium is shiny black with light pile. Pile on the opaque abdominal portions is black, while the yellow spots have yellow pile. In females, the second abdominal segment has a broad opaque black area in the middle that is narrower toward the front and extends as a band to the lateral abdominal margin at the back. The third and fourth segments each also have a narrow, interrupted shiny fascia, and the lower part of the front is not entirely covered in white pile.
Wings: The wings are hyaline, and sometimes faintly clouded across the middle and outer portions. Near the end of the marginal cell (r1), the second vein (R2+3) shows a distinct curvature into the submarginal cell (r2+3). The R1 cell is petiolate, and the R4+5 vein is curved.
Legs: The legs are black, and the hind femora are dilated. The joints, basal third of the front and hind tibiae, basal half of the intermediate tibiae, and the middle metatarsi are light yellow. The extreme base of the anterior metatarsi has a light to medium greenish tinge.
