Biosecurity New Zealand has issued new standards for the importation of processed plant-based animal feeds.
The move follows a number of instances where insects were found in shipments from Asian countries.
An investigation by Biosecurity New Zealand found 106 live insect species in eight bulk storage sites holding palm kernel, and of those seven were species not already found in New Zealand.
Documents released to Radio New Zealand under the Official Information Act show that in one instance three shipments from Malaysia were heavily contaminated with flies and maggots and had to be fumigated with methyl bromide to kill them.
In a shipment of tapioca from Thailand, Longheaded Flour Beetle and Foreign Grain Beetle were found and also had to be fumigated.
The new rules include a higher level of inspection of shipments on arrival, as well as increased treatment regimes for the products, to ensure any insects or seeds are killed off.
Federated Farmers grain council chairperson Ian Morten says because the standards still rely largely on certification from the country of origin, they do not protect farmers here.
He says there have been suggestions that such certificates "can almost be bought off the side of the road" and he would prefer closer audits of phytosanitary certificates from overseas and a closer examination of those countries which do not comply.
Mr Morten says the responsibility of who pays for the clean-up if a pest plant or insect establishes here seems to continue to lie with farmers, when it should be up to the importers.
Biosecurity New Zealand manager of plant imports and exports, Stephen Butcher, says farmers can have faith in the system.
He says officials work closely with authorities in exporting countries to make sure the certificates are accurate, continuously monitor imports and have a high level of verification of the certification process.
Plant-based stock feed has been imported into this country for years, the increase in the number of dairy farms has lifted the amount of feed imported.
