Dichotomous table for gallers on Eupatorium cannabinum
by Hans Roskam
1a Malformations of leaves at the tips of the shoots => 3
1b Swellings of the shoot stems => 2
2a Spindle-shaped or cylindrical swelling in main- or side stem near a node or in axils of flower peduncles, about 10–15 mm long, with round opening when mature; one or several yellowish-white caterpillars with a yellow-brown head, in pith with frass. Upper stem parts stunted, often conspicuously discoloured. Adaina microdactyla
2b Stem mainly close to the ground, with differently situated and expanded, sometimes curved swelling. A scale insect in a depression. Planchonia arabidis
3a Malformations by aphids or spittlebugs => 4
3b Leaves on stunted shoot tips clustered, rolled upwards, rudiments of inflorescences stunted. All infected parts conspicuously white pubescent. Aceria eupatorii
4a Aphid malformations => 5
4b Leaf segments nest-like converging, the leaf blades curled, dark green close to the froth-covered nymph. Philaenus spumarius
5a Leaves on ± stunted shoots more or less stunted, the margins curved downwards, the leaf blade ± curled. Aphid 1.5–2 mm long, bright yellowish to yellow green, with short conical yellowish to green cauda. Brachycaudus helichrysi
5b Similar malformations by dark green aphids; siphunculi and cauda dark to black. Aphis frangulae