There’s something uniquely rewarding about harvesting apples from your own tree. These trees flourish in most of the United States, with species hardy in zones 3 through 9, and there are countless famous varieties that you can cultivate. You can even grow ornamental species for their beautiful booms.
However, there are about as many pests that love these trees as there are varieties of apples you can find at your local grocery store. These apple pests range in severity; some you can just ignore, while others must be treated before it’s too late. Some damage leaves, some girdle bark, and some burrow their way right into the fruit.
Whether you’ve been growing a beloved tree for decades or are just now setting up your orchard, familiarizing yourself with these pests is a good idea. We’ve assembled a list of 13 pests you may find eating your apples or trees to guide you.
As a general note for systemic insecticides, never spray while your trees are blooming. This damages the flowers and any pollinating and beneficial insects around your trees. Many of the systemic insecticides below will damage beneficial insects anyway, so use caution when applying them in a home garden.
Wooly Apple Aphids
Wooly apple aphids are specialist pests on apple trees. They feed on the bark of new twigs just below the leaves, and they also chew around pruning cuts and other wounds or cracks. Wooly apple aphids even eat roots, which is often where they live during winter. Knobby galls form where these aphids have been feasting.
Galls on twigs and roots are the most obvious symptom of wooly apple aphids. You may also see the aphids themselves, which look like wooly masses. They also leave honeydew behind and can cause visibly curling leaves.
The galls increase in size over time and become an easy way for fungal pathogens to enter the tree. In general, wooly apple aphids slowly reduce the health of trees and make them more vulnerable to other pathogens. These aphids aren’t a death sentence, but you should still attempt to control them.
To control wooly apple aphids, keep an eye out for new colonies and galls. Include insectary plants in your orchard that invite parasitic wasps and syrphid flies to feed on these aphids. At first sight, treat with insecticides such as malathion, or you can try using a horticultural oil spray in the delayed dormant period. Note that you can treat colonies on twigs, but there’s not much you can do to control root-feeding colonies.
Other Aphids
Various other aphid pests prey upon apple trees, including the green apple aphid, rosy apple aphid, and spirea aphid. The fine details vary from species to species, but typically, these pests feed on the tree’s phloem vessels and reduce the tree’s overall strength. They also produce honeydew, which attracts sooty mold.
You may see the aphids themselves. While the green apple and spirea aphids are green, the rosy apple aphids are light pink. Additionally, aphids can cause deformed fruits or curled and sticky leaves. Sooty mold can also be an indicator of aphids. The dark mycelial threads of this fungus look like soot, making it fairly easy to identify.
Aphids are usually not enormously damaging to trees. You can probably ignore them if your tree is otherwise in good health or blast them with a strong stream of water from a hose. However, if you have a young tree that appears stunted from a serious aphid infestation, or if sooty mold is getting out of control, you may need to step in.
These aphid species have many natural predators, such as lady beetles and lacewings. If these predators don’t get the aphids first, you can apply a horticultural oil spray or insecticidal soap. Keep a healthy population of host plants for beneficial insects as a preventative measure.
Borers
Multiple borers, including the flathead apple tree borer, will prey on apple trees during periods of drought. The larvae of these pests girdle limbs and the trunks of trees, which can kill limbs and push trees into decline.
Attacks from these pests are often on the sunny side of the tree, where you will see holes with oozing sap. You may also discover a sawdust-like material which is the excrement of the borers. Flaking bark and dead limbs are also symptoms of borers.
Borers aren’t a serious threat, but they can push already-weak trees into a downward spiral. And while they probably won’t kill an entire tree, you can definitely lose some tree limbs to borers. Keeping trees in good health so that they can resist borers is important.
Unfortunately, there isn’t really a way to treat borers. You can attempt to prevent them in the first place with trunk sprays that contain ingredients like pyrethrin. Wrap trunks of young trees to block entry by borers.
The best borer prevention is overall vigor and good tree health. Keep trees well-watered, especially during drought. To your best ability, avoid damaging the tree’s roots when mowing the lawn. Remove any dead limbs quickly to avoid infestation before it escalates.
Codling Moths
The codling moth is the adult form of the classic cartoon worm that lives in apples. The moths lay their eggs on or near developing fruits, and the larvae make their way into the fruits through the end where the flower petals were attached.
You’ll know you have an issue with codling moths when you find worms in your apples or if you see entry and exit holes in the fruits. You may discover the pests’ excrement on the fruit. The apples may rot around the entry and exit holes, and the fruits may also fall right off the tree.
While codling moths won’t kill trees, they can absolutely ruin your harvest, making them a pest of paramount importance. Infested apples won’t look too appetizing to begin with, and no one wants to bite into a wormy apple.
To prevent codling moths, thin fruit regularly and remove any infested fruit as soon as it’s discovered. Try bagging apples to protect them. You can also apply various insecticides, including carbaryl and malathion, but they won’t have any effect on larvae already inside fruit.
Japanese Beetles
Japanese beetles have a distinct appearance, with metallic blue-copper bodies that shine in the sunlight. They appear mostly in June and July, feeding on the leaves of many plants. If you’re seeing this pest on your apple trees, you’re probably seeing them elsewhere in your garden, too.
These beetles make small holes in the leaves. These holes accumulate, and before you know it, there’s barely any leaf left. Japanese beetles may eat damaged fruits as well. They are easy to identify. You will almost certainly see these large, distinct pests. They won’t be hard to ID.
Thankfully, Japanese beetles don’t cause much damage to apple trees. It’s unfortunate that they chew up the leaves, but a vigorous, healthy tree can lose a bit of foliage. The beetles’ activity tends to wane by August.
You can attempt to control Japanese beetles with insecticides that include carbaryl, but repeated use can actually increase mite populations. You may want to explore Japanese beetle traps, which you must place at least 50 feet from the plants you aim to protect. If you’ve had problems with Japanese beetles in the past, try applying beneficial nematodes around the soil of your tree to prevent emergence of overwintering larvae.
Leafrollers
Multiple leafroller pests may be interested in your apple trees. While they aren’t a devastating pest to have around, they chew up leaves, roll up leaves, and lay their eggs in the leaves. Sometimes, their rolling habits connect leaves to fruits, and the leafrollers damage the fruit, too.
The main way to identify leafrollers is in the name; you will discover that leaves appear rolled. The leaves will also be clearly chewed up, and you may see webbing within them. Small cavities in fruits may also be a sign of leafrollers.
Leafrollers aren’t an enormous concern for trees, and they aren’t going to kill your tree over time. However, they can damage the fruits, which is a huge disappointment. In small or weak trees, leafrollers’ defoliation can be harmful.
These pests are easy to manage. They have many natural predators, including parasitic wasps, that may do the job for you, especially if your garden has plants to host them. If not, you can apply Bacillus thuringiensis (aka B.t.), which kills leafroller caterpillars without harming any of the natural predators you hope to preserve.
Leafminers
The spotted tentiform leafminer can cause some notable damage to apple trees. These tiny insects feed inside the leaf as caterpillars, feeding on the sap and then the tissue. This causes tent-like mines in the leaves, which may be visible on the surface.
If you notice that the leaves have these tent-like holes, you may have a problem with leafminers. These holes combine to form tunnels that lighten to white. If leaves have enough of these depressions, they may wrinkle and fall off.
Leafminers usually will not cause significant damage and aren’t a cause for alarm. However, if you have a particularly gnarly infestation, enough damaged foliage can lead to reduced crop quality and reduced tree growth.
These pests are typically kept in line by very efficient natural predators, such as parasitic wasps. If you’re struggling with leafminers and natural predation doesn’t seem to be doing the job, try applying spinosad. This natural option can get to the leafminers inside the leaves and kill them.
Mites
Various mites can be an issue for apple trees, including spider mites. These tiny arthropods are actually arachnids, like spiders; they are not insects. Spider mites appear when it gets hot and dry during the dog days of summer, removing chlorophyll from the leaves.
You can identify a spider mite infestation by looking closely at damaged leaves. They may have a stippled look, where the spider mites sucked out the sap and chlorophyll. The spotted areas may have a bronze appearance, and the leaves may look scorched. If infestations are high enough, you will see webs.
Low populations of spider mites are not a huge deal and will likely not be a problem for your apple tree. Natural predatory mites are usually enough to keep spider mites from getting out of control. You can remove spider mites manually with a sharp spray of water. If that doesn’t work, you can try an insecticidal soap or horticultural oil spray.
Other mites found on apple trees include the European red mites and apple-leaf blister mites. You can control European red mites with horticultural oil, and you can ignore apple-leaf blister mites, which are rarely a problem at low populations.
Plum Curculios
Plum curculios are weevil pests that live near apple trees in winter, emerging when the weather warms up to lay their eggs in fruits. They typically appear just as temperatures start to consistently hit 70°F (21°C). These weevils can cause misshapen fruits that prematurely fall.
You may see the plum curculios themselves, which are about ¼ inch long. They have dark bodies with gray patches and a long snout. You can also identify them by the crescent-shaped cuts they leave in fruits to lay their eggs.
While these pests aren’t devastating to the entire tree, they’re detrimental to the fruits. The growing fruits often kill the larvae inside, but the blemish remains. Infested fruits will usually drop to the ground anyway.
Remove any infested or fallen fruits right away. If you have wild plum trees around, consider removing them. You can also try covering the fruits with kaolin clay, which may block the weevils. If necessary, you can control them with sprays that contain cyhalothrin or zeta cypermethrin.
Stink Bugs
Stink bugs are more than just a nuisance in the home; they can damage your apples, too. They feed on young fruit, injecting it with saliva that kills plant cells near the bite. Then, they drink the fruit’s juices. Visibly depressed areas form in the fruits where stink bugs have eaten.
Regarding ID, you’ll be able to see these bugs. They usually are shield-shaped with a flat back. Though there are multiple species, one of the more common culprits is light brown. They’re about ½ inch long, so they won’t be hard to see.
Stink bugs won’t be a huge detriment to your apple tree, though they will damage the fruit. The reduction in fruit quality can make it unmarketable. Not only will the fruits be marked, but the interior texture also becomes corky and dry.
A large tree with a small population of stink bugs should still produce plenty of good fruit. If you have a serious enough stink bug problem to warrant removal methods, spray with a product that contains cyhalothrin or zeta cypermethrin. Keep stink bug host plants like mallow, vetch, morning glory, and plantain far from your apple trees to prevent them.
Tarnished Plant Bugs
Tarnished plant bugs are similar to stink bugs when it comes to their method of damage. They feed on the young fruits, creating holes and sucking out the juices, eventually leaving pitted, damaged fruits in their wake. Sometimes, entire clusters of fruit will drop.
Your best bet at identifying this pest is to spot the bugs themselves. They’re about ¼” long, so they’re smaller than stink bugs but still visible. The bugs are usually a brownish shade of yellow, with an oval body and a “Y” marking between their wings.
Like stink bugs, tarnished plant bugs aren’t going to kill your tree and aren’t an emergency. They can, however, damage your fruit and cause plenty of it to drop. Keep an eye on these pests to make sure the infestation doesn’t grow.
If you’re intent on removing tarnished plant bugs, you can use a spray containing cyhalothrin or zeta cypermethrin. Removing early-blooming weeds near your apple trees can generally reduce the number of both tarnished plant bugs and stink bugs.
San Jose Scale
There are many species of scale insect pests, and multiple feed on apple trees. The most notable are San Jose scale insects. They feed on bark and fruit, extracting the sap. San Jose scale insects are tiny, with each one measuring about 0.1 inch in diameter, but their infestations can be large.
If you discover fruits that are covered in what look like dark flakes, these are the San Jose scale bodies. You may also see bark and tree limbs covered in these small insects, which look like pepper. You’ll probably also see what looks like red circles with white centers all over the fruits.
These scale insects can kill entire tree limbs and make fruit unmarketable. If you struggle with San Jose scale insects or have had problems with them in the past, a preventative method is best to keep things under control.
One female San Jose scale insect can produce 400 more scale insects within a month and a half, so don’t delay in pest control. A few weeks of uncontrolled spread can be significant.
To control them, spray 2% horticultural oil on the trunk and branches in early spring before the leaf buds begin to open. Then, your best bet is to stay on top of this problem all season long, directly spraying any crawlers you find with further diluted horticultural oil spray.
Speckled Green Fruitworms
Speckled green fruitworms are small fruitworms larvae that frequent apple trees and other fruit trees. They feed on newly emerged leaves, flowers, and young fruits. These fruitworms are active for about six weeks per year in spring.
You can easily ID this pest, as it looks like a green worm. The youngest speckled green fruitworms are about ¼ inch long and a bit grayish. As they mature, they become green and reach a length of nearly two inches. They’re hard to miss.
You may notice other symptoms as well. Speckled green fruitworms leave chewed up foliage in their wake, as well as deep, round holes in fruits. You may also experience fruit drop earlier than expected.
Fortunately, speckled green fruitworms are not horribly detrimental to apple trees. If you see them, there’s no need to panic, as the tree is not in danger. However, you may experience a reduced harvest, so treatment may be appropriate regardless.
These pests are as easy to control as they are to identify. A single application of insecticide such as Bt or spinosad should get the job done. If you have experienced speckled green fruitworms in previous years, apply the insecticide preventatively right after petals fall.
