Citrus Pests
The Usual Suspects
Citrus trees, much like many other plants, can be the unfortunate victim of pest attacks. Keep reading below to learn more about some of the most common citrus pests, along with some things you can try to minimise the damage they do.
Citrus Leafminer
What are they?
The citrus leafminer is a small nocturnal moth that lays its eggs on the underside of new leaves. The eggs hatch into tiny grubs that mine their way through the leaf.
What do they do?
After the grubs hatch, they mine, or tunnel, through the leaves which is what causes that silvery-coloured damage trail which will eventually fade to brown.
After this stage, they curl the edge of the leaf over and form a chamber to pupate. Once they hatch again into a little moth, the cycle begins anew.
Leafminer won’t kill the tree and it doesn’t affect the fruit; it only distorts the new growth.
How do I fix this?!
Once the damage is done, it cannot be repaired. Affected leaves can be pruned off and disposed of carefully, just in case there are any larvae or cocoons are left over.
On established trees, the leafminer isn’t a particularly major threat. However, on young trees, taking preventative measures is your best bet as they can be quite damaging.
Spraying trees with ‘Eco-Oil’ or ‘Eco-Neem’ every 3 weeks leading up to and during “leafminer season” can help control outbreaks. These two products can actually be mixed together into the same sprayer and used simultaneously for additional protection.
At times, you may need to alternate products into your insect spray routine to ensure better coverage and control of any infestations. Some other products we use are Yates Success Ultra Insect Control or Yates Nature’s Way Citrus & Ornamental Spray.
As always, when using any products in the garden, be certain to read the instructions and bio-safety information to understand what you’re using and if it’s right for your garden.
Stink Bugs
What are they?
Stink bugs, also known as the ‘Bronze Orange bug’, are a multi-stage insect that are native pests of citrus trees. They start their lives as small green insects before maturing into the typically orange or bronze shield-shaped insects we usually see on our trees.
What do they do?
Stink bugs lay their eggs around late spring to early summer. Once those hatch, the first stage insects don’t actually feed on the tree, so this is a great time to remove them. Most of the damage is done by the late-stage nymphs or adult insects.
Once they start feeding, they suck the sap out of new growth causing it to wither and die. They also attack flower stalks and budding fruit, causing those to drop off as well.
A few of these insects can decimate younger trees, and whole infestations can do significant damage even to established trees.
As the name implies, the insects have an unpleasant smell. They secrete a foul acid as their main defense mechanism which can be harmful to skin and eyes.
How do I fix this?!
Prevention is the best defense with stink bugs. Keep an eye out for their eggs on the underside of leaves in late spring-early summer and remove them before they hatch.
You can use an insecticide like Yates Success Ultra Insect Control or Nature’s Way Citrus & Ornamental Spray by Yates as part of your citrus care regime. They often work on the younger stages of these insects, so getting in early and creating a pest control routine will be most effective against stink bugs in the long run.
Since the adults are notoriously difficult to control, in conjunction with spraying, we recommend physical removal.
There are a few ways you can do this, but our favourite method is to use an old vacuum cleaner to suck up the insects. You can then empty the vacuum into a bucket of hot, soapy water to destroy them. You can also use extra-long BBQ tongs to pick the stink bugs off if you prefer.
You can often find them on really hot days when they hide on the underside of leaves to stay cool.
As always, use caution and wear protective gear when removing stink bugs! They spray a defensive acid when predators get too close, and you definitely don’t want it on your skin or in your eyes as it can be quite damaging.
Caterpillars
There are a few different caterpillars that attack citrus, chewing large irregular holes in the leaves. They can vary in colour, from black to green with colourful stripes or spots and have small fleshy spines on their bodies.
Length can vary from 15mm to 50mm long depending on their larval stage. Can be controlled by hand removal or spraying with a suitable insecticide, such as, ‘Maverick’. Although it should be noted that these caterpillars turn into lovely large citrus butterflies and a few chewed leaves are not going to kill the tree.
Snails
The common garden snail can cause extensive damage to the leaves and fruit of citrus, especially oranges. They start by attacking young leaves by chewing holes in them leaving a skeletonised effect.
As fruit ripens they can also attack the skin, chewing right through to the flesh. Control them by using regular snail baits following the instructions on the pack, and be careful of your animals.
Scale
There are a number of different scales that affect citrus trees and include both soft and hard types. They attack most parts of a tree, from the stems and trunk (White Louse Scale), to the fruit (Red Scale).
Soft scales produce large amounts of honeydew, which ants love, and this can lead to Sooty Mould forming. Hard scales do not produce honeydew but can blemish fruit or cause leaf drop. High populations can cause the death of trees. Less toxic sprays such as ‘Eco Oil’ and ‘Pest Oil’ can help to stop this problem, repeated sprays will be necessary.
Sooty mould as a result of previous scale and aphid infestations.
Aphids
Aphids affect many types of plants including citrus.
These small sap sucking insects, usually green or black normally attack the fresh new growth, distorting the leaves and excreting honeydew, which then causes the secondary problem of sooty mould and ants.
They attack in plague like proportions, with literally thousands gathering on the ends of new shoots. The safest chemicals would be “Pest Oil’, ‘Eco Oil’, pyrethrum based sprays or ‘Yates Natrasoap’.