Frequently Asked Questions

Could didymo spread to lakes throughout New Zealand?

Yes. Although didymo prefers a river environment with clear water flowing over stable substrate at depths sufficient for light penetration to drive photosynthesis, blooms have been found in South Island Lakes. Lake Wakatipu, for example, contains visible didymo on some parts of the lake shore.

If I see something I think is didymo, what should I do?

If you see something you suspect is didymo in an unaffected river, please report the location of the find to the Ministry for Primary Industries on 0800 809 966.

Hydrilla - Frequently Asked Questions

Frequently Asked Questions: PDF Link to PDF document (354 KB)

For more information please see Hydrilla page.

How do other countries manage Varroa?

If varroa is established in a country, a successful approach for the beekeeping industry is likely to include:

  • not destroying infested hives;
  • developing smart movement controls and applying them judiciously;
  • very promptly getting overseas expertise to upskill the industry (and regulators) on what management and regulatory approaches to take;
  • surveillance to monitor the spread of varroa and alert beekeepers to the need to control;
  • putting a lot of resources into beekeeper education on management and control;
  • working out ways to coordinate control on an area basis;
  • carrying out research to identify the best management practices for controlling mites under local conditions;
  • taking a strategic approach to registering chemical controls.
What attempts are being made to find and destroy all the GM Zebra danio fish out there?


We are using various tracing methodologies to try to locate all the fish from both the original consignment and sales records. MAF BNZ will also be working directly with members of the aquarium fish community for information and seeking their support in tracing fish.

What does the painted apple moth look like?

The painted apple moth is recognisable once you know what to look for.

There are five stages in the painted apple moth life cycle -- egg mass, larvae, pre-pupae, pupae (cocoon), and adult moths -- and the pest looks quite different at each stage. The painted apple moth is most distinctive in the larva (caterpillar) stage, when it is brightly coloured, hairy and easily recognised by the tufts of hair on its back. (No native caterpillars are hairy like the painted apple moth.)

What does the name Didymosphenia geminata mean?

Didymosphenia, derived from the Latin 'didymos', means double. Likewise, geminata, derived from the Latin word 'geminus', means twin born, paired or double. Both of these words refer to the bilateral microscopic shape of the organism which looks like a curved bottle with paired bulbous ends. This is due to the pairing of two halves of the silicified cell wall which fit together like a Petri dish, with one half slightly smaller than the other.

How can the spread of didymo be stopped?

Freshwater pests such as didymo can be spread by a range of human activities (e.g. angling, kayaking and tramping through waterways). ‘Check, Clean, Dry’ is the title of the decontamination method which, when carried out ensures gear that is being moved between waterways is free of didymo. This decontamination method prevents further spread of didymo to waterways where it may not be present. For more detail on the Check, Clean, Dry cleaning procedures, refer to these cleaning instructions.

Changing freshwater hygiene behaviour so that the spread of current and potential freshwater pests can be restricted is managed by actively promoting and raising awareness of the Check, Clean, Dry procedure.

The Check, Clean, Dry campaign and the Freshwater Pest Partnership Programme are led by the Ministry of Primary Industries. The campaign focuses on providing Check, Clean, Dry information to waterway users. A number of key stakeholder and partners work together on the Partnership Programme.

If I see something in the river, how do I know if it is didymo or not?

Didymo can be distinguished from other species of algae on the basis of:

  • Colour - didymo is beige/brown/white but not green.
  • Touch - Although it looks slimy, it doesn't feel slimy, but rather spongy and scratchy like cotton wool.
  • Odour - Live didymo has no distinctive odour.
  • Strength - didymo is very securely attached to river stones and does not fall apart when rubbed between your fingers.

However, didymo can easily be confused with other stalked algae, so microscopic analysis is required to confirm identification.  Please phone the Ministry for Primary Industries on 0800 80 99 66 if you think you have found didymo.

My business has lots of daily foot traffic. Do I need to maintain a visitors record?

Depending on the facility and if risk goods are present:

If a facility is able to control access (eg customer and couriers are coming to one area to pick-up and drop-off items) then a visitors book might not be necessary.

In general, there should be no public access where uncleared risk goods are held.