Populus nigra, Hungary, Mosonmagyaróvár, 21.v.2018 © László Érsek
this mine is unusually transparent . . .
. . . enabling to see the frass pattern
Populus nigra, Duin en Kruidberg
two oviposition scars (they are not always are positioned marginally!)
Four Zeugophora species are known from Europe: flavicollis, frontalis, scutellaris, subspinosa and turneri.
All five species make large, blackish-brown upper-surface blotches. The eggs are deposited at the leaf underside; they are inserted in a small pit, that is covered by secretion (Urban, 1922a). This oviposition site remains visible as an orange transparant spot in the mine, often near its border. The larva is yellow, flattened, and legless. They live in a small group in the mine, vacating the mine before pupation through an upper-surface exit slit. See Heinig & Schöller (2012a) or Warchalowski (2003a) for a key to the imagines.
Only shortly ago I discovered the key to the Zeugophora species of North America and Europe by Jong Eun Lee (1998a). Unfortunately, Jong Eun Lee has not taken Z. frontalis or Z. turneri into account. Quite confusing however is that he states that the mandibles of the other three European species have mandibles with 2 teeth, while both Steinhausen (1994a) and Urban (1922a) write that flavicollis has 3 mandibular teeth. Also an illustration of the larva of Z. scutellaris in Lawson (1991a) shows three, equally sized, teeth.
The pictures of the larvae therefore have to do without a specific name for the time being.
Heinig & Schöller (2012a), Jong Eun Lee (1998a), Lawson (1991a), Urban (1922a), Warchalowski (2003a).