Aggregators such as the Atlas of Living Australia (ALA) and the Global Biodiversity Information Facility (GBIF) have recently been criticised for imposing "backbone taxonomies" on records provided by museums, herbaria and other sources. Taxon names may be changed to suit the backbone, with the result that the taxon rank of the record may change and the originally provided name may no longer be searchable online through the aggregator. Aggregators may also delete data items, either by omitting entire fields or rejecting data items not conforming to aggregator-specific data standards. Modifications are more common than deletions and are particularly worrying in geospatial, date and recorder data fields. It can be difficult to locate originally provided data on aggregator websites, even for individual records, and bulk downloads from aggregators typically mask the changes made. In this presentation I document the loss and modification of biodiversity data items by aggregators and suggest strategies for museums and herbaria to counter data loss and modification.