Some insects, such as psocids, tobacco beetles, silverfish and cockroaches, are known to be common in stored plant material such as is found in herbaria. In order to curb explosions in insect numbers buildings are fumigated on a regular basis. Fumigants such as ethylene dioxide, methyl bromide organic phosphates and phosphorus hydride are used in some herbaria but, because of environmental and occupational health and safety concerns and the impracticality of completely sealing the building, only pyrethrin-based fumigants are used at the Gardens.
In order to reduce the need for frequent fumigations, strict quarantine and decontamination of specimens entering the buildings is employed. This involves freezing at temperatures of less than -18 degrees Celsius for at least two days, which is sufficient to kill insect pests and their eggs. If specimens are needed urgently for comparison they are treated in a microwave oven to kill insects and their eggs.
Standard quarantine procedures, meeting Australian Quarantine Inspection Service specifications for the control of insects, will be applied to specimens entering the collection. Freezers will be inspected and certified annually by officers of the Australian Quarantine Inspection Service.