Polylectic with strong preference for Hedera helix (Araliaceae). Males have been seen visiting the flowers of Eryngium amethystnum (Apiaceae)(Gogala, 1999) and on Jersey, males have been seen visiting Calluna vulgaris (Ericaceae) flowers close to a nesting aggregation (B. Bolton, pers. comm.).
Recent evidence suggests that C. hederae seems to be more flexible with respect to its pollen hosts than hitherto believed. 2 pollen loads of C. hederae from Switzerland were composed of 100% Odontites (Orobanchaceae) pollen resp. 65% Hedera and 35% Asteraceae pollen; 5 pollen loads from central Italy were composed of: 95% Calluna (Ericaceae) and 5% Hedera; 95% Asteraceae and 7% Hedera; 75% Hedera and 25% Calluna (Ericaceae); 72% Hedera, 15% Asteraceae and 13% Calluna (Ericaceae); Asteraceae 82% and Hedera 18%. (Müller pers. comm).
Müller & Kuhlmann (2008) list as pollen sources: Hedera (Araliaceae), Cichorioideae and Asteroideae (Asteraceae) and Odontites (Orobanchaceae) based on 41 pollen loads from 24 different localities.
Westrich (2008) reports similar foraging strategies in southern Germany, particularly early in the season. In the first half of the flight period of the year 2006 the pollen loads contained a high proportion of pollen of Asteraceae (Aster type, Taraxacum type), Fabaceae (Melilotus type, Medicago type) and especially Colchicaceae (Colchicum type) beside an increasing amount of Araliaceae (Hedera type), as time progressed. The most abundant pollen type was identified as Colchicum autumnale. Comparing the pollen types with the plant species of the surroundings showed that the females had collected pollen from the following plant species: Solidago canadensis, Cosmea bipinnata (Asteraceae); Medicago sativa, Melilotus albus, Trifolium repens (Fabaceae); Colchicum autumnale (Colchicaceae).
Westrich also observed Colletes hederae collecting pollen from non-host pollen sources in southern France, where females foraged at Odontites viscosus (Orobanchaceae). In south-western Germany females foraged at Solidago canadensis and Solidago gigantea (Asteraceae) At these sites Ivy was only partly flowering.
Peeters (2010) reported females nectaring on Reseda alba (Resedaceae) in the Netherlands. Müller & Kuhlmann (2008) found pollen loads that consisted entirely of pollen from shrubs in two museum specimens. They also found four mixed loads of pollen from Hedera helix, shrub, and Asteraceae from the subfamilies Asteroideae and Cichorioideae.
In north western France, individuals have been seen at flowers of Tamarix sp. (Tamaricaceae) before Hedera helix was in flower (Moenen, 2004) and nectaring at Odontites luteus (Orobanchaceae) http://www.flickr.com/photos/nico_bees_wasps/7894270222/in/photostream