Dichotomous table for gallers on Mespilus germanica
by Hans Roskam
1a Malformations on leaves => 3
1b Galls on shoot axis => 3
2a Young shoots with small bulge-like, oval swellings, which contain the causer in a central depression. Epidiaspis leperii
2b Older shoot stems with spindle- to club-shaped swellings. Viscum album
3a Galls caused by aphids => 5
3b Galls induced by other causes, locally delimited => 4
4a Underside of leaf blades with felt-like pubescence. Eriophyes pyri
4b Yellowish or brownish bulges on the underside of leaf blades, rotund-oval, elongate spindle-shaped on venation, developing fibrous aecia that tear open. Gymnosporangium confusum
5a Extensive malformations caused by aphids => 6
5b Leaf margin rolled downwards. Aphid covered with white woolly wax. Prociphilus pini
6a Leaves on stunted shoot tips hardly discoloured, strongly rolled and curled; aphid 2 mm long, leaf- to dark-green with dark brown-black siphunculi. Aphis pomi
6b Similar malformations; aphid yellowish-green, with segmental dark-green stripes on back and pale siphunculi, only dark at tip. Rhopalosiphum oxyacanthae