Common Citrus Tree Pests

In addition to the edible fruit, a citrus tree (Citrus spp.) has glossy, green leaves and fragrant blooms that add a subtropical accent to sunny yards in U.S. Department of Agriculture plant hardiness zones 8 through 10, depending on the variety. Unfortunately, various pests also find citrus trees attractive. The most common pests of backyard trees include various sapsucking insects, caterpillars and ants. Recognizing citrus pests allows you to treat problems before the insects cause too much damage.

Sapsuckers, such as whiteflies, spider mites, scale insects and aphids, prefer feeding on new leaves in spring. All of those soft-bodied pests also secrete an abundance of honeydew, which encourages the growth of sooty mold fungus and also attracts ants.

Aphids, tiny, pear-shaped insects that group together in colonies, suck the sap out of plant tissue, causing curled, misshapen leaves and stunted foliage growth. Young citrus trees might experience stunted or distorted growth with large infestations, but mature trees typically withstand aphid attacks and don't need treatment.

Whiteflies, particularly the aptly-named citrus whitefly (Dialeurodes citri), also feed on citrus foliage. Whitefly larvae feed beneath the leaves, and large populations cause wited or yellowed foliage and prematurely falling leaves.

Scales insects, such as the leaf-feeding citricola scale (Coccus pseudomagnoliarum), are tiny insects that quickly settle down in one feeding spot, where they stay for the rest of their lives. These small pests feed on fruit, leaves and stems, often causing severe fruit and leaf drop. High scale populations can reduce the overall health of the citrus tree and reduce the number of blooms and fruit the tree produces.

Spider mites have eight legs and tiny, round bodies hard to see without a magnifying glass. Mite feeding activity can cause yellowed, blistered, stippled or misshapen foliage and leaf drop. Leaf drop can be severe on sensitive varieties such as 'Sunburst' tangerines (_Citrus reticulata '_Sunburst,' USDA zones 8b through 11). Look for the fine webbing the mites spin beneath and between leaves and between citrus fruit.

Scales, whiteflies, aphids and spider mites can be controlled with insecticidal soap, a low-toxicity pesticide that won't harm people, animals and most beneficial insects. It's also safe to use on food crops. Purchase a ready-to-use spray bottle to control pests on small trees. For larger trees, one product recommends mixing 5 tablespoons of soap concentrate for every 1 gallon of water, but follow the manufacturer's directions on your specific product. Pour the mixture into a small garden sprayer and completely coat the foliage and branches. This pesticide doesn't leave any residual chemicals behind, so you must make direct contact with the pests. Start spraying when you first notice the pests and repeat once every seven days until pest populations disappear.

Apply soap solution to a small section of the tree and check for damage 24 hours later. If no burning occurs, apply it to the entire canopy.

You can spray citrus trees with insecticidal soap solutions up until the day of harvest. 

Dislodge soft-bodied citrus pests by giving the foliage a forceful spray of water from a garden hose.

Spray on calm days when no rain is expected for the following 24 hours to keep the solution on the foliage.

Soaps can irritate your skin and eyes, so wear goggles, a face mask, long sleeves, long pants and waterproof gloves to prevent injury. 

Don't spray drought-stressed plants or when it's hotter than 90 degrees Fahrenheit or you increase the risk of burning. 

Avoid spraying blooming citrus trees so you don't harm pollinating insects. 

Various ant species can become pests on citrus trees, including Argentine ants (Linepithema humile), native gray ants (Formica aerata) and fire ants (Solenopsis spp.). Ants usually become problematic when soft-bodied pests excrete sweet-tasting honeydew. The ants help protect the honeydew producers so their natural enemies can't reach them. Fire ants also damage freshly planted citrus trees by feeding on the bark and twigs. Grapefruit trees (Citrus paradisi, USDA zones 10 to 12) are particularly vulnerable to fire ant attacks.

Placing bands of sticky material on tree trunks is the easiest way to stop ants from reaching honeydew. The University of California's Integrated Pest Management program recommends using a polybutene-based product.

Applying the sticky material directly to the trunk can cause cracking, so wrap a 6- to 18-inch piece of thick paper or material around the trunk and spread the sticky material on top of it. Place the wrap several feet off the ground so it's out of direct sunlight and won't be affected by sprinkler water. Regularly check the sticky substance, rubbing it with a stick to get rid of collected dust and renewing the material as needed.

Remove branches hanging within 1 foot of the ground so ants can't easily climb into the tree.

Take care around fire ants because the pests can deliver nasty bites.

Caterpillars, particularly orangedogs (Papilio cresphontes) and puss caterpillars (Megalopyge opercularis), feed on citrus trees. Orangedogs are the mottled brown and gray larvae of giant swallowtail butterflies. The caterpillars can be up to 2 inches long. The caterpillars feed on citrus foliage and can totally strip young trees of their leaves.

Puss caterpillars, the larvae of the southern flannel moth, reach about 1 1/2 inches when they're ready to pupate and grow thick coats of grayish-colored hair. Although they might look furry and cute, these pests are also called "stinging asps" because the hairs have venom glands at the bases that cause painful burning sensations if you touch them. Never handle puss caterpillars with your bare hands. Beyond their ability to inflict pain, the puss caterpillars can also strip citrus trees of their leaves when they feed.

Bacillus thuringiensis kurstaki is a natural, soil-borne bacterium that naturally kills leaf-eating caterpillars by poisoning their digestive systems. After eating the bacterium, the caterpillars stop feeding and die within a few days.

Follow the directions on the product's label. One product recommends mixing 1 tablespoon of Btk concentrate for every 1 gallon of water. Place the mixture in a handheld sprayer and thoroughly cover all leaves and stems on the tree. Begin treating the citrus trees when you first notice a pest problem and repeat every seven days until you achieve control.

You can control orangedogs on small citrus trees by squishing the caterpillars and their eggs.

You can apply Btk sprays up until the day of harvest. 

Btk is also toxic to all butterfly larvae, so don't spray any citrus trees within 300 feet of butterfly gardens.

Btk solutions cause eye irritation, so put on protective eyewear when mixing and spraying this product. 

Don't spray citrus tree if rain is predicted in your area in the next 24 hours.