The parasitoid assemblages associated with grass-feeding chalcid wasps in G
reat Britain were used to examine the relationships between diversity (spec
ies richness), community function (total parasitism rate) and stability (va
riability in parasitism rate over time). Species-rich communities did not g
enerate higher parasitism rates than species-poor communities, nor was temp
oral variation of parasitism rates related to parasitoid community richness
. The mechanisms underlying hypotheses linking species richness and communi
ty function and stability are discussed in the light of these results. Beca
use all parasitoid species represent a single functional group, a lack of c
omplementarity in the ways they use their resources may explain why diversi
ty is not linked to function or community stability. A second likely reason
is that these parasitoid communities are under bottom-up control, thus exe
rting little or no influence on total system function and variability. This
is likely to be common in parasitoid communities.