One form of policing occurs by the oophagy of the worker-laid eggs, found in many ant and bee species. This could be done by both or either the queen or the workers. In a series of experiments with honeybees ("Apis mellifera"), Ratneiks & Visscher found that other workers effectively removed worker-laid eggs in all colonies, whether the eggs were from originated from the same colonies or not. An example of a combination of queen and worker policing is found in ants, in the genus "Diacamma", in which worker-laid eggs are taken by other workers and fed to the "queen". In general, these signals that identify the eggs as queen-laid are likely incorruptible, since it must be an honest signal to be maintained and not be used by cheating workers.