Dichotomous table for gallers on Ballota nigra
by Hans Roskam
1a On leaves => 2
1b Shoot tips or lateral buds disfigured, leaves ± converging, discoloured, rolled upwards and inwards, also unopened and ± bud-like. Containing several white (yellow), jumping larvae. Contarinia ballotae
2a Upper leaves, including shortened petioles, swollen and succulent at base, sometimes additionally pubescent. Containing yellowish-white larvae. Unidentified gall midge
2b Leaf blades at shoot tips or in inflorescences slightly bent in at margin, ± arched and slightly curled. Brachycaudus ballotae