The most probable reason that your orange tree leaves are sticky is that you have an infestation of sap-sucking insects. These insects – and there are quite a few different types – leave behind honeydew, that’s the sticky substance. Here’s how to identify which insect is your problem and what to do about it.

Honeydew

Sap-sucking insects suck the sap out of your orange tree leaves and stems for their food. In doing so, they excrete and leave behind blobs of a clear, sweet and sticky substance called honeydew.

By itself, honeydew doesn’t harm your orange tree. However, it does attract a fungal disease called black sooty mould, which I describe in Orange tree pests and diseases. In addition, honeydew attracts ants, which are a pest that you don’t want to see on your plants. Though this occurs more frequently during the time your orange tree is outside in your garden.

All in all, it’s best to identify which bug is causing the sticky leaves and do something about it.

Sap-sucking insects

These are the most likely culprits to be dropping honeydew on your orange tree.

Mealybugs

These are pick and flat, oval shaped insects. They’re not too small to see with the naked eye but they do hide in out-of-the-way parts of the tree. Check under the outer layer of stems and in the leaf sheafs. Mealy bugs quickly grow from just a few to a large infestation.

What to do

Isolate the orange tree from all other plants. Cut off the parts of the tree that are infected.

Aphids

The aphids that you may encounter on your orange tree are mainly whiteflies, greenflies and blackflies. They look like tiny flies (around 1.5mm long) with wings and small bodies. Once again, they’re easier to see when you have a lot of them on your tree.

What to do

Use sticky tape to remove the aphids from your tree. or use a water spray to knock them off. Natural horticultural oils such as neem oil applied to the plant help prevent further infestations.

Spider mites

Spider mites are even smaller than aphids and mealy bugs. They’re really too tiny to see, except as green or brown-red blobs when many of them gather together. Look instead for spider webbing on the leaves.

What to do

Dislodge the mites with a stream of water. Do this outdoors so the water doesn’t spray the mites into the air and over other plants. Trim the infected leaves and stems and spray with neem horticultural oil.

Other common sap-sucking bugs

These are some other common honeydew-producing sap-sucking bugs that infest indoors plants. They may also be the reason that your orange tree leaves are sticky.

Soft scale insects

Soft scale insects are around 6mm long, so you can see them up close. They usually group together on the underside of leaves and stems. They have a waxy shell that protects them from spray insecticide solutions.

What to do

A few of these won’t harm your orange tree, but watch for their expanding into a large group. Pick individual scale insects off by hand. Spray the plant with natural neem oil or pyrethrum soap to help get rid of them.

Thrips

Thrips are insects that you definitely won’t see as they’re too small to find even with a magnifying lens. You can tell you have a thrip infestation through if the buds, flowers and fruit of your orange tree become mottled and look ravaged. Look for a new silvery colour on the flowers and buds as a tell-tale sign.

What to do

Go straight to using an insecticidal soap that’s safe for citrus trees. This will either get rid of the thrips or the thrips will win the battle. If your tree succumbs to the trip infestation, you must destroy the tree before the thrips spread to all your other plants.

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