Anyone who’s had a citrus tree will be familiar with bronze orange bugs.
Also called stink bugs, they produce a foul-smelling secretion and suck the sap from stalks, causing flowers and fruit to drop.
These pests need to be controlled in winter before they can build up their numbers in spring and summer.
They lay eggs on the underside of leaves with the young, called nymphs, appearing in winter.
The nymphs are flat, lime green and about 6mm long.
As they mature they turn orange or bronze and become rounded, going from brown to black and reaching 25mm long as adults.
Methods of control
Numbers of bronze orange bug build up rapidly, making control difficult, so take action immediately.
A high population may be a sign the tree is stressed.
Give it a deep watering and apply a citrus fertiliser.
Wear goggles to control bronze orange bugs, as they expel a caustic liquid that can cause severe irritation.
For small trees, blast them off with a jet of water from the hose then collect in a bag and squash, or drop into a bucket of methylated spirits.
Large trees should be sprayed every 10 to 14 days with Eco-Oil or Confidor to kill the nymphs before they develop into breeding adults.
You may also notice green bugs with sharp shoulder spines. Native to Australia they’re called spined citrus bugs.
They like lemons and mandarins but suck sap from other citrus fruit.
This pest causes young fruit to develop flat patches of skin and brown stains on the flesh.
Treat them the same way as bronze orange bugs but you’ll have to look a little closer to find them, as their green colour helps them blend in well.
One way to treat small nymphs in winter is with a soap spray, concentrating on the underside of leaves and the lower part of the tree.
To make the spray, add one tablespoon of pure soap flakes, such as grated Velvet soap, to half a bucket of warm water.
When the soap has dissolved in the water, fill a spray bottle and treat leaves early in the day.
TIP: Don’t use any sprays on hot days, as this can damage stressed plants even more.