gallers on Lythrum

1a On parts above ground => 2

1b Roots with nodular, compact swellings. L. salicaria: Meloidogyne hapla

1c Swelling in root; containing a chamber with a weevil larva. L. salicaria: Hylobius transversovittatus

2a Malformations on various vegetative as well as generative parts => 5

2b Globular to spindle-shaped galls on shoot axis => 3

3a Galls caused by weevils. In the gall a legless, curved weevil larva => 4

3b Weak, oblong swellings close to shoot tip. L. salicaria: Unidentified gall midge

4a Long spindle-shaped or rotund swelling, usually one-sided, succulent, one- or more-chambered on lower parts of shoot axis. Apically organs sometimes severely stunted. L. hyssopifolia, ? salicaria: Nanomimus hemisphaericus

4b In similar one- or more-chambered galls. L. hyssopifolia, salicaria: Nanomimus circumscriptus

4c Side shoots with a swelling, up to 8 mm long, rotund-oval, one-chambered. Containing a single larva. L. portula: Dieckmanniellus gracilis

4d Slender spindle-shaped stem galls, 12–18 mm long, usually at leaf insertions of several L. hyssopifolia, junceum, salicaria: Dieckmanniellus nitidulus and/or D. helveticus

4e Small conspicuous swelling of stem, laterally protruding, variously expanded. L. acutangulum, hyssopifolia, salicaria: Nanophyes globiformis

4f Inconspicuous swelling of the stem. L. salicaria: Nanophyes rubricus

5a Malformations mainly involve unfolded leaves => 6

5b Lateral buds or tips of vegetative shoots disfigured. All leaves of infected axillary buds severely stunted, adnate at base, developing into a gall up to 6 mm long, ± reddened with free terminating apex over differing length. Infestation of shoot tip results in stunting of axial parts with tuft-like clustering of basally largely stunted leaves. Infected flower buds swollen at base; calyx hardened. Stunting of all other parts; usually unopened. Depending on gall size a single or several orange-yellow larvae. L. salicaria: Bayeriola salicariae

6a Malformations caused by aphids or spittlebugs => 7

6b Petioles swollen over a length of about 10 (15) mm, slender pear-shaped. Galls succulent, one-chambered. Leaf blades severely stunted. Containing a single larva. L. hyssopifolia, salicaria: Nanomimus circumscriptus

6c Minor swellings of leaf. L. portula: Chlorochytrium rubrum

7a Malformations caused by aphids => 8

7b Leaf blade deflected, curled, locally deep green; infestation close to shoot tip results in one-sided stunting and distortion of axial parts, associated with clustering of similarly disfigured leaves. L. salicaria: Philaenus spumarius

8a Clustering of disfigured leaves or also failed flowers on ± stunted shoot tips caused by aphids, about 2 mm long, pale to yellowish-green. L. hyssopifolia, salicaria, virgatum: Myzus lythri

b8 Clustering of ± stunted, deflected and curled leaves on less stunted shoot tips or similar malformations on several lower situated leaves caused by black aphids. L. salicaria: Aphis fabae