  If dark matter interacts with quarks or gluons, the mediator of these
interactions is either directly accessible at the LHC or is so heavy that its
effects are encoded in contact operators. We find that the self-consistency of
a contact operator description at the LHC implies bounds on the mediator scale
stronger than those found from missing energy searches. This translates into
spin-independent elastic scattering cross-sections at a level < 10^-41 cm^2,
with direct implications for the DAMA, CoGeNT, and CRESST-II anomalies. We then
carefully explore the potential of monojet searches in the light mediator
limit, focusing on a Z' model with arbitrary couplings to quarks and dark
matter. We find that the Tevatron data currently provides the most stringent
bounds for dark matter and Z' masses below 100 GeV, and that these searches can
constrain models for the DAMA, CoGeNT, and CRESST-II anomalies only if the
mediator can decay to a pair of dark matter particles.
