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[Vol. 88 
nid Andrena wilkella (Linsley 1958). At my study site, the honey bee 
is far the most abundant of these species (Ginsberg 1979). In the 
1950’s, honey bee populations declined sharply in New York State 
due to the increased use of pesticides and the decline in farm acreage 
devoted to buckwheat, an important food source for honey bees 
(Morse 1975). Before 1950, therefore, honey bees were even more 
common than at present. 
Apis mellifera is a high-density specialist in flower foraging. Its 
large colony size and recruitment capabilities facilitate this special- 
ization (Eickwort and Ginsberg 1980; Sakagami 1959). In spring, 
honey bees forage on high-density resources such as rosaceous trees, 
willows, and clusters of roadside herbs. In late summer, honey bees 
forage on the super-abundant goldenrods, also high-density re- 
sources. 
In early summer, honey bees are relatively rare on the old field 
(Table II). At this time of season they forage primarily off the field 
on high-density resource species in forests and on cultivated fields 
(Farrar 1944; Ginsberg 1979). The introduced herbs that bloom at 
this time are exploited by primitively social halictines (Table III). 
The multivoltine seasonal cycles of these bees allow them to build 
up their populations over the season, thus they can exploit the 
recently introduced flower species that are now abundant in early 
summer. Ceratina, which is probably univoltine in the Ithaca area, 
is also common in early summer, but it forages somewhat earlier 
than the halictine bees, and is most common on native flowers such 
as Rubus spp. (Table III). 
An interesting result of this analysis is that each of the major 
historically novel instances of resource abundance is exploited by 
social bees. Honey bees forage on rosaceous trees and roadside 
weeds in spring, and on goldenrods in late summer. Native bees 
forage on these flowers also, but honey bees predominate because of 
their high populations and recruitment ability, both features related 
to their social behavior. Social halictines predominate on intro- 
duced herbs in early summer because of their broad host ranges and 
their multivoltine seasonal cycles, also related to their sociality. Ap- 
parently, the ability to adapt to landscape-level changes in resource 
availability is an important advantage that accompanies social 
behavior in bees. This does not mean that only social insect species 
can adapt rapidly to changes in resource levels. It does suggest that 
in bees, sociality facilitates this rapid adaptability. 
