Nysius, wheat bug

Scientific name: Nysius huttoni

Nysius adult

Nysius feeding damage to swedes

Nysius adult

Nysius nymph

Nysius nymph
  • Key characteristics
  • Biology
  • Impacts
  • Control

  • Common throughout New Zealand
  • Prefers open ground
  • Particularly common in warm dry areas
  • Has a wide food range which includes many plants of agricultural and horticultural significance but also many weed species
  • Can be very damaging to germinating brassica crops especially when these have been direct drilled
  • The adults are often noticed on bright days when sunlight reflects from their wings giving them a silvery appearance.

  • This insect is found throughout New Zealand although it is more numerous and damaging in warm dry areas, and prefers crops that are open and where sunlight reaches the ground. It attacks a very wide range of crops and weeds
  • The eggs when first laid are creamy white but turn deep orange by the time they hatch. There are 5 nymphal stages and as development proceeds through these stages wings become increasingly more obvious. The small nymphs are dark orange in colour but the later stages become grey or brown-grey. The first stage is approximately 0.5 mm long and subsequent stages increase in size until eventually they reach about 2 mm. The adults, with fully developed wings, are about 4 mm in length and typically dull brownish-grey. Their wings however reflect light giving them a silvery appearance that catches the eye. Nymphs on the other hand can be very difficult to see and it is very easy to underestimate how many are present.

  • Damage to brassica plants is due to feeding punctures made around the base of the plants. While seedlings are small this can directly cause plant deaths. With larger seedlings this feeding causes cankerous tissue growth or stem restrictions that appear similar to ring barking. These cause production losses and may kill the plants or make them susceptible to breakage from wind and stock movement. The damage is often more severe in direct drilled crops where up to 87% of plants have been measured as damaged and 70% killed as a result of nysius feeding. Fodder beet seedlings are similarly damaged.

Chemical control

  • Several insecticides and formulations are registered to control nysius. As damage to newly emerging seedlings is particularly destructive paddocks should be inspected for nysius before sowing and appropriate action taken. Numbers can be hard to assess accurately, a rule of thumb would be to consider control if three or more can be seen in a 10 x 10 cm area. Post emergent sprays can be used in response to damage but while these may be very effective in killing nysius, damage to the crop may have already occurred so they should be applied as early as possible.

Registered insecticides (active ingredient) formulation and type of application for control of nysius

Insecticide

Formulation

Application
imidacloprid seed dressing applied to seed before sowing
chlorpyrifos emulsifiable concentrate, capsule suspension sprayed before or after sowing
Permethrin+pirimiphos-methyl emulsifiable concentrate spray at first sign of insects
Spinetoram aqueous suspension apply during early post emergence
terbufos granule drill with seed