Flower-Visiting Insects
of Common
Horehound
Marrubium vulgare (Common Horehound) introduced
(Insects suck nectar; one observation is from Krombein et al. as indicated below, otherwise observations are from Robertson)
Bees (long-tongued)
Apidae (Apinae): Apis mellifera fq; Apidae (Bombini): Bombus griseocallis, Bombus pensylvanica; Anthophoridae (Ceratinini): Ceratina dupla dupla; Megachilidae (Megachilini): Megachile brevis brevis
Bees (short-tongued)
Halictidae (Nomiinae): Nomia nortoni nortoni (Kr)
Flies
Bombyliidae: Bombylius atriceps
Butterflies
Pieridae: Pontia protodice fq