Persicaria knotweed

The classical genus Polygonum has been split into Bistorta, Fallopia (incl. Reynoutria), Persicaria, and Polygonum.

Dichotomous table for leafminers

1a small, brown, tentiform mine: Calybites phasianipennella

1b corridor: Chromatomyia horticola

1c blotch, may be preceded by a corridor => 2

1d galls, etc => Tables for all parasites per species

2a large blotch, not preceded by a corridor; larvae communal; at the start of the mine mostly a group of some elongated egg shells => 3

2b blotch preceded by a narrow corridor; larva solitary; no egg shell visible: Agromyza polygoni

3a larva: mandible with some fine teeth: Pegomya bicolor

3b mandible with ± 3 large teeth: Pegomya solennis **

** It is possibly that also Pegomya setaria, primarily a miner of Fallopia-species, may occur now and then on Persicaria; there is no possibility to discriminate the larva from that of P. solennis.

Not included in the key: Mantura rustica.