Bugwatch: Bronze Orange Bugs
Just when your poor citrus tree thought it would be safe to put on some new growth, finally mustering up the energy to grow again after a long and productive fruiting season, this dreaded pest arrives with its stinky, squirty spray, sucking all the vigour from the new spring shoots.
Yes, its stink bug time again. But this year we say enough. This year it’s time to put our heads together, find the best weapon and ward them off. This year we mean business!
The dreaded Bronze Orange Stink Bug. Photo - Linda Ross
Symptoms: These prolific pests will damage citrus trees, often causing fruit to drop. Bronze orange bugs will suck the sap from the tree, flowers and fruit will subsequently fall and stems can turn discoloured and die.
Bronze orange bugs are out in force during warmer months. This pest appears first in late winter as a light green nymph, making it hard to spot. As bronze orange bugs develop they change colour into the more familiar orange to bronze. Some bird species will consume these pests but often not enough to control and prevent damage to plants. Assassin bugs will also predate bronze orange bugs, yet still they seem to endure.
Bronze Orange Bug eggs. You can see the bugs inside. These bugs will reproduce rapidly, so one or two could quickly turn into an infestation. Photo - Emily Shepton
A Bronze Orange Bug emerges from the egg. Photo - Emily Shepton
The Nymphal bugs appear green, then change to orange with a brown spot in the middle of their backs. Photo - Andy Burton
Solution: It is best to start your pest management program in early spring while bugs are young. Spray products such as Eco-oil fortnightly to provide an organic defense. Apply good coverage to leaves including their undersides.
If infestation has already begun, or indeed taken hold, spraying with an insecticide is probably unavoidable. Use a naturally based insecticide with natural ingredients including Pyrethrum, like Richgro Beat-a-bug, or Yates Nature's Way Citrus & Ornamental Spray, which is the only spray registered with the APVMA for home garden control of Bronze Orange Bug on edible citrus. Use as a contact spray to knock them down, then treat the foliage with a horticultural soap to deal with the eggs left behind. Insecticides containing Imidacliprid, such as Confidor, will be effective. But the unintended consequences on beneficial insects, like bees, will also be severe. Resist the urge to use Imidacliprid insecticides when citrus are in flower, and never on edible fruit.
Other organic remedies many gardeners employ include sucking up pests with an old vacuum cleaner, removal by hand and drowning them in methylated spirit, or crushing them between planks of wood. But all of these method put the gardener in harm’s way. If you must engage these pests hand-to-hand make sure you wear gloves, long sleeves, protective glasses and a hat or other protective clothing. Bronze Orange Bugs emit a foul-smelling, citric-acid-rich liquid when disturbed and this can be very dangerous, particularly if sprayed in the eyes.
The mature Bronze Orange Bug and a nymphal bug underneath. Photo - Jan Anderson