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Lemon Tree Pests: How to Identify and Prevent

Lemon trees are amazing for their bountiful harvests of great-smelling lemons. They also have attractive foliage and come in a variety of sizes. However, there are lemon tree pests that can attack your lemon tree and cause a host of problems. Here are some of the lemon tree pests that you should watch out for in order to keep your tree as healthy as possible. 


Lemon Tree Pests: Aphid close up on a green leaf.
Aphid close up on a green leaf.

Aphids are tiny bugs that can be hard to see with the naked eye. They often look like tiny green dots, though they can come in other colors like red, black, brown and white. Chances are that if you notice them, it’s because there are large masses of them on your tree. These lemon tree pests may be small, but they can cause an enormous amount of damage. They drink the sap from stems and leaves and can very quickly cause harm to your tree. 

You will often see aphids in the spring when there is new plant growth. It’s a good idea to check the new growth each year to make sure there aren’t aphids on it. If you do find aphids, there are a number of ways to get rid of them. Many people swear by their method of blasting these bugs with water to get them to dislodge from the stems and leaves.

This can work, depending on the area of the tree you are spraying, but it is unlikely to get rid of every aphid if you have a large population of them. One single aphid being left behind can lead to a population of 600 billion of them in a single season.

There are specialized pesticides that can be used for aphids. These come from a variety of makers and are extremely effective sprays that take little time to get rid of these lemon tree pests. However, many owners want to use something natural to both deter and get rid of aphids. You can actually make your own deterrent made from either tomato leaves or garlic oil. Both of these can create effective sprays to get rid of aphids and a variety of other insects. 

Another way to both deter and kill aphids is to get ladybugs on your tree. This can be done by either buying cups of ladybugs from a gardening store or finding them in the wild. Planting dill, carrots or dandelions, as well as other plants with frilly leaves, will attract ladybugs. Companion planting these near your tree can help to keep ladybugs in the area. 

Citrus Leaf Miners

Citrus Leaf Miners
Citrus leaf miner damage on lime leaves

Leaf miners are bigger than aphids, but are still quite small. They are actually a variety of tiny moths. They can cause so much damage to a young tree that it causes its growth to be stunted as well as making it more susceptible to disease. 

One of the best ways to recognize these insects is to look for the way they affect leaves. They tend to curl up part of a leaf as they go to work on it and mine their way through the leaf’s outer layer so that it can feed on the softer portion below that layer. You may also see passageways winding around on a leaf that has been mined. 

Once a lemon tree is mature it can stay healthier despite an infestation of these insects, but if their numbers are big, it can reduce the amount of fruit the tree produces. There are many pesticides that will kill these lemon tree pests. There are also a few preventative treatments that can be used to keep these pests away.

Putting some mesh at the bottom of the tree can make it harder for this insect to complete its lifecycle. You can also use neem oil to keep these bugs away or to kill ones that have already moved in. It is diluted with water and then used to water the plant. There are also a number of spray poisons of various types that can be used to kill these tiny bugs. 

Asian Citrus Psyllid

Asian Citus Psyllid
Asian citrus psyllid in lime.

These lemon tree pests are known for both causing damage to citrus trees and for introducing harmful bacteria to them. These bugs are another tiny insect variety that can infect young trees and new growth. When you inspect your lemon trees for pests, take care to notice whether there are any burned leaf tips or any leaves that are twisted.

Both of these are signs of the Asian citrus psyllid. These bugs have toxic saliva and as they feed on new tree growth, they get that toxic substance into the tree. They can also introduce bacteria to the tree that can cause a serious tree disease called citrus greening. Once this disease has set into the tree, there is no way to cure it. 

To prevent this disease, you can get rid of the bugs as soon as you see them or prevent them from infesting your tree. There are a number of sprays that can be effective on these lemon tree pests. If you see these bugs, you can have a licensed pest control technician come out and spray the tree with specific insecticides that will work.

Many of these are not sold to the public. However, you can also use an insecticidal soap or a horticultural oil to combat these bugs. Both can be effective against this pest. There is also an over-the-counter imidacloprid insecticide remedy called Bayer Advanced Fruit, Citrus & Vegetable that can be used in summer and fall when watering the tree to keep these bugs away.


A close up of a greenhouse whitefly infestation on a citrus leaf showing adult whiteflies and their eggs

Whiteflies are small insects that can be seen with the naked eye. They look like small white flying insects, though you may see their residue before you see them. They can make the leaves look moldy or scaly if they have been eating from your tree.

They can also cause its leaves to curl up. Often, the whitefly stays on a lemon tree from the beginning of spring right through the fall, and its larvae hatch there are eat the sap from leaves. This is what causes the curling. There are several different types of whiteflies that can infest lemon trees, but they all eat the underside of leaves, and they tend to congregate in large numbers.

Because their numbers can grow so quickly, it is important to catch an infestation in its earliest stages. If the infestation gets bad enough, it can mean the death of the tree. 

If the areas of infestation are small, it’s smart to simply prune away those areas. If you do this, be sure to dispose of the clippings properly so that the whiteflies don’t spread elsewhere from those clippings.

You can seal them in a bag or burn the clippings. You can also get rid of any ants that are around the tree. Ants often defend whiteflies against predators because they like to eat the residue that whiteflies leave behind.

If you get rid of the ants that defend them, there will be more predators to take care of the whiteflies. You can also introduce ladybugs to the tree. These brightly colored bugs eat both aphids and whiteflies. 

You can also knock many of these flies off the tree with a blast of water. However, you may want to employ a number of methods to be sure that all of these lemon tree pests are killed. Most of the broad-spectrum insecticides on the market will not kill these pests.

There are, however, various horticultural oils and insecticide soaps that will work on the young whiteflies when temperatures are cooler. They can be put directly onto these bugs in order to kill them. You may need to apply them once a week to make sure that all of the young bugs are killed. 


Leafroller Caterpillar
Leafroller caterpillar on a green leaf

These lemon tree pests are well-known for the way they roll up the leaf of a tree. They grow to about 2.5 cm in length, and they can be green or brown. When a see a leaf that is completely rolled up, chances are that you have this caterpillar.

They will roll a leaf together and then use silk to tie it closed. In these nests, they will start eating the leaves. If you have just a few of these nests on your tree, it is often not a big deal. However, if they start to build up in numbers, serious damage can be done to the tree. If there are a lot of them, they may start to eat the lemons as well as the leaves, and the tree can lose its leaves.

Two Curled Leaves
Two leaves curled by leaf roller caterpillars

If you just have a few to remove, cut out the rolled-up leaves and put them into some soapy water. Then, check weekly to make sure that their numbers aren’t coming back. If you have more than just a few of these lemon tree pests, you will likely need to use a chemical remedy to get rid of them.

One such remedy, bacillus thuringiensis, can be applied to the leaves where it will be eaten by the leafrollers. Then, this substance will poison their stomachs and disrupt the lifecycle of these lemon tree pests. It is especially effective when leafroller caterpillars are young. There are several different kinds of leafrollers, so all of them on your tree may not hatch all at once. They also differ in how many generations they can hatch, with some being able to create two generations a year. 

Before you use any kind of pest control for these bugs, be sure that you remove as many of the affected leaves as possible. Then you can treat the affected leaves to make sure that no more will hatch. Some types of these insects can lay up to 300 eggs in a season.

They should be found in the spring and killed then rather than allowing them to mature into moths in the later summer. Another insecticide that you can use is called spinosad. However, it’s important to be careful with this type, as it is poisonous to bees. Don’t use it just before a storm or on flowers. 

Beneficial insects can also help to control the population of these pests Ground beetles, lacewings, spiders and several other bugs are the predators of leafrollers. And, they are a natural way to kill this pest without using poisons that can be harsh on the environment. 

Inspect Your Lemon Tree

It’s always easier to get rid of an infestation of pests when you get to it earlier rather than later. Younger bugs are more vulnerable to insecticides and oils that can be used to get rid of them. To make sure that you aren’t missing an infestation, check your tree once per week. Take a look at the leaves and see whether there is anything that is adversely affecting them. Once you see that an infestation is in progress, it will be much easier to eradicate it than if you wait for the pests’ numbers to get exponentially higher. 

Ready for more lemon content? Next, visit our lemon trees page to discover more useful and fun information on lemon planting, growing, harvesting, cooking, and more!


Wednesday 23rd of August 2023

what insect is leaving the small white powdery spots on my key lime tree? it is on the stems and under the leaves. what can i do to get rid of it?


Tuesday 29th of August 2023

Sounds like powdery mildew to me.