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Updated 18 November 2019 11:02am

What is encapsulated cyanide or Feratox?

Feratox is the trade name for an encapsulated form of cyanide that is used for possum control in New Zealand.

How is Feratox used?

Encapsulated cyanide pellets (Feratox) are dispensed to possums from bait bags or placed directly into a non-toxic feed paste.

The feed paste is placed into bait stations and bait bags are stapled to trees.

Bait bags contain one to two Feratox pellets (47.5% cyanide - 475g/kg) which are incorporated within the non-toxic feed paste. This is dyed green.

To release the cyanide poison, possums have to chew hard enough on the Feratox pellet to crack it in their mouth, releasing the cyanide.

Feratox bait will be placed within treatment areas at 10 to 100 metre intervals at a height of 0.5 to two metres above ground level.

Bait stations are initially checked every two to three days and refilled as necessary.

Feratox pellets that get dislodged to the ground by rats will perish and break down in the soil once wet.


Feratox bait bag


Small round Feratox pellets and non-toxic feed paste used as possum bait. 

Important points to remember

  • Warning signs will be erected at all main access points where Feratox is laid
  • You need to read and adhere to the instructions on these signs
  • Feratox and non-toxic feed paste will be dyed green
  • Feratox pellets will be incorporated in the non-toxic feed paste and placed in bait bags which are stapled to trees 

Danger to humans

Children should be kept away from all poisoned areas. If you suspect bait has been swallowed, get medical help immediately.

Cyanide is a rapidly acting toxin. It inhibits the enzyme systems that transfers oxygen to body cells and affects the part of the brain that controls breathing.

Typical symptoms include:

  • Dizziness
  • Rapid breathing
  • Headache
  • Drowsiness and unconsciousness.

Consuming one Feratox pellet will kill an adult weighing 73kg. Even less will kill a 15kg child.

Contact the National Poisons Centre 0800 764 766 in an emergency


This poison is fatal to humans. Speed is essential. Seek medical help immediately.

Use artificial respiration if breathing has stopped (mouth to nose).

If swallowed, give a glass or two of water and induce vomiting by putting a finger down the throat. 

Repeat until the vomit fluid is clear in appearance. 

Do not attempt to cause vomiting if the patient is unconscious or convulsing.

Danger to dogs and cats

Both dogs and cats are extremely susceptible to cyanide baits if they are eaten directly. 

Cyanide breaks down rapidly inside possum carcasses leaving little or no poison residues.

There is a low risk of secondary poisoning to dogs and cats that eat possum carcasses.

Dead possums may have poison residues around their mouth or on their paws.

Do not handle possum carcasses or let dogs scavenge them.

Why do we use cyanide?

Cyanide has been used for possum control in New Zealand since the mid-1960s for the following reasons:

  • It is fast acting – possums become unconscious within one minute and die three to four minutes later
  • It is effective for use in high possum density areas
  • Baits are small and easy to lay so large areas can be treated by hand
  • Possums die on the spot, allowing fur and skin recovery
  • There is low risk of secondary poisoning.

Feratox can only be used by Certified Approved Handlers or by persons under their direct control.

Cyanide is a vertebrate toxic agent (hazardous substance) under the Hazardous Substance and New Organisms Act 1996 and the Agricultural Compounds and Veterinary Medicines Act 1997.