Top eight pests to watch

10 June 2005

Below are just eight pests and diseases that are the focus on the campaign, but there are many more undesirables that threaten New Zealand's economy and environment. Information on other nasties can be found on Biosecurity NZ's website at  .


  • This starfish is a predator which can form large groups to feed in particular on mussels and other shellfish beds.
  • It has 5 rays (arms) with pointed upturned tips and is yellow, orange or red with purple markings on top and uniformly yellow on bottom.
  • Several NZ native seastars look similar BUT these natives lack the distinctive upturned tips of the Northern Pacific seastar and differ in colour.
  • It measures 10 cm across and is present in Australia


  • The water hyacinth is an invasive water weed that has mostly been found in Northland and Auckland but also as far south as Wellington.
  • Each plant consists of a free-floating rosette of shiny, rounded leaves and a thick mass of feathery roots hanging in the water.
  • From the rosette a single flowering stalk can grow up to 50 cm high – a cluster of 5-15 mauve-blue flowers tops it.
  • Each plant can produce 3-4 daughter plants at the end of its stolons, which in turn produce further plants that can form dense mats.


  • Can infect all bird species – but intensive poultry rearing systems (young fattening turkey and laying hens) are usually most affected.
  • Avian Influenza has infected people handling poultry.
  • Symptoms; sudden, unexplained deaths, rapid spread of disease through flock, depression, lack of appetite, drop in egg production, nervous signs, swelling and blue combs and wattles, coughing, sneezing and diarrhoea.
  • Mortality is extremely high with deaths up to 100% over just a few days.
  • It has never been present in New Zealand


  • This insect is of concern to NZ because it is capable of spreading Pierce's disease, which infects grapevines and would be extremely detrimental to our viticultural sector.
  • It also feeds on citrus and avocado trees.
  • Long distance spread of the glassy-winged sharpshooter is through the movement of infested plant material – the insect lays its eggs into the underside of leaves.
  • Eggs and young nymphs are difficult to detect. The adult sharpshooter is large at 13-14mm, and has strong flying ability.


  • This pest has been found in New Zealand before, and surveillance programme is underway.
  • The webworm eats a wide range of fruit and broadleaf trees and shrubs etc and damages trees during its larval (caterpillar) stage.
  • When the caterpillars hatch they spin a silken web around the leaves of a tree and begin to feed on that foliage. You are most likely to notice the large, silken webs.
  • The caterpillars themselves are yellow to green in colour and are covered in long white/grey hairs. They have a black stripe down their back – and yellow racing stripes down each side.
  • The moths are about 2.5-4cm in wingspan.


  • This snail is considered one of the most damaging land snails in the world.
  • Distinctive in appearance to NZ snails as it is large in size and has a relatively long, narrow conical shell.
  • Can reach up to 200mm in length but more commonly is up to 100mm.
  • Colour can be variable but is most commonly light brown with alternating brown and cream bands on young snails and the upper whorls of larger snails.
  • Normal food for the Giant African Snail consists of decayed vegetation and animal matter, lichens, algae and fungi.
  • These snails can live up to 9 years – it can enter a state of hibernation and can survive months in this state often being mistaken as a dead specimen.


  • These wood-boring beetles look very similar as they are closely related.
  • Serious pests in Asia, they have the potential to pose a serious threat to New Zealand's environment and economy.
  • Entry could most likely happen through imported timber or woods used for packing material from Asia.
  • The larvae tunnel into the heartwood of the tree – feeding can cause branch breakage and ultimately tree death.
  • Larvae are creamy white, with a brown mark on front side while adult beetles are 20-35mm long, shiny black with about 20 white dots on wing-covers and striped antennae.
  • Adults emerge in summer from trees or timber from holes, often leaving piles of sawdust at the base of the trees or branch crevices.


  • This highly-contagious viral disease is endemic in many parts of the world but has never broken out in New Zealand
  • The disease affects primarily sheep, cattle and pigs, causing lesions to appear on the underside of the hoof, in the mouth, labia, muzzle or snout.
  • Although it's not usually fatal, the animal's recovery is prolonged, causing enormous economic losses.
  • The emergence of Foot and Mouth Disease here would have serious consequences to New Zealand's agricultural and dairy industries


Last Updated: 27 September 2010

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