Red-brown-white Ptocadica Flea Beetle (Ptocadica bifasciata)

("RBrWh"; "RBW"; "Strabala sp. red-brown-white" in notes)

This Ptocadica species feeds primarily Passiflora auriculata and is occasionally found on other Decaloba (on P. biflora 15% of the time; once on P. lobata). Pt. bifasciata often sits under leaves or on foliage next to the host plant. A good flier, Pt. bifasciata can hover and examine the foliage before alighting. As shown in the photo below, they sometimes scrape the leaves when feeding. Unlike many of the other species of Passiflora-feeding flea beetle, Ptocadica bifasciata is seldom seen in groups. Typically each beetle will be on their own branch, or be seen sharing a branch with other species such as Yellow-legged Parchicola or Monomacra violacea.

Larvae of Pt. bifasciata may be seen feeding on leaves and walking the stems. I have not yet seen eggs, but predict they will be round, laid on the undersurface of the host plant leaves (like Red Ptocadica). The white and rose colors turn brown in dried museum specimens, but the dark melanic spots remain. There is also variation in the degree of melanization on the elytra, with some individuals much darker and with more contrast between brown and white (see photos below). The genetic barcode analysis did not distinguish the two color forms, however. Perhaps they are developmental or depend upon host plant.

I have found P. biflora plants with larvae and multiple individuals of Pt. bifasciata, suggesting that this species can reproduce on P. biflora. This should be confirmed, however.

In our early collections, this species was listed as "Strabala sp. red-brown-white".

Feeding on the preferred host P. auriculata. Scraping the upper leaf surface of P. auriculata.
Pt. bifasciata larva on P. auriculata Note paler dark spots on rear of elytra.