Lemon trees are prone to pest attacks that range from insects, rodents, bugs, larvae, and gastropods. Pests typically attack the tree’s leaves, fruit, twigs, and stems. Extensive damage can cause stunted growth, leaf fall, and even some citrus tree diseases.
Identifying potential pest incursions early is crucial for effectively controlling them from spreading.
11 common lemon tree pests
Here are the most common pests on lemon trees:
Aphids are small insects that can cause damage to your lemon trees. Aphids attach themselves to leaves, twigs, and other soft tissues where they suck sap from the plant’s phloem.
You can tell if your lemon tree has an aphid infestation by manually inspecting it for insects using a magnifying glass. A sticky goo, also called honeydew, on the plant’s leaves and fruit can also indicate a recent infestation on your lemon trees.
Signs of an aphid infestation on your lemon trees include:
- Curling leaves on lemon trees
- Yellowing citrus leaves
- Slowed plant growth
- Stunted and drying shoots
- The presence of soot mold on leaves and fruits
- Sticky substance on the leaves
You can use organic, biological, and chemical control measures to get rid of aphids on your lemon trees. I use Neem oil or a solution of garlic + pepper + vinegar to control these pests.
Here’s a homemade aphid spray recipe for your lemon trees.
- 1 oz of water
- A clove of garlic (15 pieces)
- 1 tablespoon cayenne pepper
- 1 tablespoon vinegar
Slightly crush garlic and add it to a pot with water, cayenne pepper, and vinegar. Boil for about 15 minutes, then cool and strain. Add the solution to a spray bottle with 10ml liquid soap. Spray the infested lemon trees to kill the aphids and their eggs for good.
2. Citrus leaf miner
The citrus leaf miner (Phyllocnistis citrella Stainton) is a small, winged insect that lays eggs on the underside of your lemon tree leaves. Once the eggs hatch, the larvae burrow inside the leaf as they feed on the soft tissue inside the plant.
You can tell if your lemon tree is suffering from a citrus leaf miner attach by checking for small silver-like coloring within the leaf veins. You can also insect your plant’s leaves for the presence of eggs on affected surfaces.
Key indicators of citrus leaf miner infestation include:
- Malformed leaves
- Stunted growth
- Reduced fruit size
- Evidence of tiny brown moths on lemon trees
Chemical sprays and biological predation are effective ways to safeguard against citrus leaf miners. I recommend products that contain imidacloprid for treating and controlling these insects on your citrus trees.
A good product I have used for my citrus trees is the BioAdvanced Fruit, Citrus, and Vegetable Insect Control.
3. Citrus rust mite
The citrus rust mite “silver mite” (Phyllocoptruta oleivora) is a common pest affecting lemon trees growing in humid conditions.
The pest affects mature trees and causes damage to leaves, twigs, and fruits. You can identify citrus rust mites by inspecting sections of your plant using specialized equipment.
Adult citrus rust mites appear as small yellow-colored specks with an average size of about 0.15mm.
Signs of citrus rust mite infestations include the following:
- Considerable fruit damage
- Presence of small egg clusters in leaf depressions and cracks
- Reduced fruit yield
It’s crucial to deal with citrus rust mite infestations early because the pests can spread quickly to other trees, making them difficult to control effectively.
Natural control measures such as introducing predatory mites and pesticides can effectively deal with rust mites.
4. Lemon bud moth
The lemon bud moth (Prays citri) is an average-sized brown insect that attacks lemon trees when blossoming.
Adult moths lay eggs on young flowers and fruit to produce larvae that feed on the affected sections. Lemon bud moth larvae also feed on the tree’s leaves (and other soft tissue) where they cause extensive damage to blossoming plants.
Key indicators of lemon bud moth infestations include:
- Internal and external damage to lemon fruits
- External damage to lemon tree leaves and flowers
Control measures for bud moths include chemical insecticides and pheromonal sprays. Spraying chlorpyriphos-rich insecticides is an effective deterrent against such pests.
5. Mediterranean fruit fly
The Mediterranean fruit fly (Ceratitis capitata) is a small brown-yellow winged pest that affects lemon trees by feeding on the tree’s fruits.
Female fruit flies attack mature fruit before ripening. They burrow small holes into the fruit and lay several egg clusters. On maturity, the larva starts to eat the fruits causing extensive damage.
Signs of Mediterranean fruit fly infestations include:
- The presence of adult flies around ripening fruit
- The appearance of small black larvae from affected fruits
- Low fruit yield
Dealing with Mediterranean fruit flies involves destroying their breeding grounds, decaying fruit, long grasses, and using insecticides to eradicate adult populations.
6. Crusader bugs
Crusader bugs (Mictis profana) are large brown insects with a conspicuous “X” on their backs. The bugs feed on young lemon tree shoots where they extract sap from the plant’s soft tissues.
Crusader bugs are easy to identify owing to their large size and conspicuous features. The insects also secret a strong unpleasant smell when disturbed as a deterrence from predators.
Indicators of a crusader bug infestation include:
- Wilting shoots and flowers
- Secretion of sap through holes left on the plant after the insects feed
- Yellow-white blotches on leaves
- Deformed fruits and leaves
- Citrus leaves fall off in some cases.
Effective control measures include handpicking, chemical control, and predation. Birds and spiders regularly feed on the insects while insecticides prove useful when dealing with large-scale infestations.
7. Citrus gall wasp
The citrus gall wasp (Bruchophagus fellis) is a notorious black/brown pest that attacks lemon tree stems and twigs.
The insect causes swellings (galls) to appear on affected plants, leaving them vulnerable to breaking and diebacks.
Adult citrus gall wasps measure about 3mm or less in size, making them difficult to see. The wasps lay eggs in the galls, which then hatch in spring to produce numerous young insects.
Here are the signs of citrus gall wasp on citrus trees:
- Swellings on young twigs and stems.
- The emergence of small black insects during spring.
- Branch/ twig diebacks.
- Reduced growing vigor.
Gall wasps have a limited flying range, making them easy to control. However, large-scale infestations require a collective effort by community members.
The best organic treatment for citrus gall wasps is to cut off the affected branches, then seal the swellings with plastic bags and put them in the sun to bake the wasps until they die.
8. Citrus scale
Scales (Coccomorpha) are small insects that suck plant sap to cause tissue damage to affected sections of your citrus tree. The insects exhibit a wax-like covering that protects their soft tissue from the elements and predation.
Scales have different physical variations that can be challenging to distinguish from other sap-sucking insects.
However, unlike aphids, they become immobile when feeding, an aspect that makes it easy to control them.
Key signs of a scale infestation include:
- Wilting leaves
- Premature leaf drop
- Presence of wax-like clusters on the underside of leaves
- Blemishes on fruits and twigs
Effective scale control strategies include a combination of cultural practices, biological measures, and chemical treatments. Regular pruning can help control scale infestations by improving airflow and sunlight exposure.
Mealybugs (Pseudococcidae) are small-bodied insects that feed on plant sap. The insects appear as small white specks on leaves, twigs, and other soft tissues.
Adult insects measure between 1.2 mm and 5 mm in size. Mealybugs cause damage to plant tissues by puncturing small holes in sensitive parts of your lemon tree.
High mealybug populations can be detrimental to your lemon tree as they leave the plant vulnerable to fungal and bacterial infections.
Signs of mealybug infestations include:
- Stunted growth
- Yellowing leaves
- Premature fruit and leaf drop
- Evidence of sooty mold
Control: Mealybugs are vulnerable to predation from ladybugs, hoverflies, and ants. If you have a citrus garden, introduce ladybugs to predate on them and reduce their populations.
Alternatively, spray rubbing alcohol on the insects to get rid of mealybugs on indoor citrus trees.
10. Rats (rodents)
Rats are formidable pests that can easily damage lemon tree fruits, twigs, and leaves. The rodents occasionally gnaw on the tree’s bark causing extensive tissue damage to sensitive sections of your tree.
You can tell if your lemon tree is suffering from rats and other rodent attacks by checking for bite marks on fruits, twigs, and stems. Rodent populations can explode if left unchecked, especially when growing lemon trees in an outdoor setting
Key indicators of rat infestations include:
- Evidence of bite marks on stems, fruits, and twigs
- The presence of rat droppings on leaves or at the base of the plant
- Physical presence of rats within the vicinity of your lemon tree
Dealing with a large-scale rodent infestation can be challenging. However, you can opt for biological control measures, traps, and bait to keep their populations in check.
11. Snails and slugs
Snails and slugs might attack lemon trees, where they feed on young shoots, ripening fruit, and young tree bark. Brown snails (Cornu aspersum) are a highly widespread species that cause damage to lemon trees.
You can tell if your citrus tree is under snail attacks by checking for signs of chewing on the leaves, twigs, and fruits. Snails also leave a slime trail which makes them easy to spot.
Key signs of snail infestations on lemon trees include:
- Presence of several snails within a lemon tree
- Circular bitemarks on leaf margins
- Several slime trails on lemon tree leaves and fruits
You can use several control measures when dealing with a snake infestation. One method involves physically picking up the snails and moving them away from our trees. Snails are also vulnerable to predation; birds, snakes, and other predators regularly feed on the pests.
You can also use a combination of chemical deterrents and cultural practices to keep their numbers in check.
I’ve used Neem, and it has controlled most of the insect problems on my lemon trees. I probably have about 20 citrus trees that I’ve grown from seedlings to 7ft tall, and all are healthy because I do routine neem oil sprays.
Until I had about 10 trees, the only bad bug I saw were spider mites. I’ve noticed over the years that the more trees you have, the more bugs you will have. Be very vigilant when buying or bringing home new plants. Some I’ve gotten were infested with bad bugs, so it is a good idea always to quarantine new lemon trees first.
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