The avocado tree has become one of the most popular tree species grown by residents of southern California.
Some grow these trees for their delicious fruit, while others simply appreciate the way they look or the shade they provide. But regardless of your motivation from growing these fruit-bearing trees, you’ll need to familiarize yourself with some of the insects that often damage them.
We’ll try to help you do so below, by explaining six pests that attack avocado trees. By learning the habits and basic biology of the following insects, you’ll have a better chance of recognizing infestations at the early stages.
1. Avocado Thrips
Avocado thrips – known to biologists as Scirtothrips perseae – were first documented in California back in 1996, and they’re currently found throughout the state.
Adult avocado thrips are yellow-brown in color and have three red dots between their eyes, which makes them pretty easy to distinguish from other thrip species. Larval avocado thrips are usually white to bright yellow in color, and they’re also found on the trees in many cases.
Avocado thrip adults and larvae are typically spotted feeding on the undersides of immature leaves and fruit. Infestations can also be detected by noting the scarring their feeding behaviors cause to the tree’s fruit (the skin of avocados on infected trees is often likened to “alligator skin”).
2. Western Avocado Leafroller
Western avocado leafrollers are important pests of avocado trees, and they also feed on citrus trees in some cases. As adults, these leafrollers have orange to brown wings with scattered dark markings, but it is the larval (caterpillar) stage that causes problems for avocado trees.
The caterpillars, which reach about ¾ to 1 inch in length, are typically bright yellow-green during their first few instars, but they become darker green with time. To verify their identity, look for a single dark mark on each side of the caterpillar’s thorax – no other avocado-feeding caterpillar bears such markings.
These caterpillars feed on the leaves of avocado trees, and they occasionally cause significant defoliation. You may also notice these insects by observing the rolled-up leaves they use while pupating.
3. Long-Tailed Mealybugs
Several mealybug species can attack avocado trees, but the long-tailed mealybug is the most likely one to infest avocado trees. Nevertheless, positive identification of the mealybug species infesting your trees is crucial to implementing a proper management plan.
Mealybugs cause damage to avocados in a few different ways. They feed on phloem sap, which can cause trees to suffer from a loss of vigor if the insects occur in high numbers. Sick or stressed trees may also struggle to endure the feeding activities of these insects.
Additionally, mealybugs can spread sticky honeydew over the plant’s surfaces. This often leads to the growth of black sooty molds, which may damage any fruit present.
4. Omnivorous Looper
The omnivorous looper is a generalist predator that feeds on a variety of different plant and tree species. It is often found in low numbers in the habitat, but disruptions to local food webs can allow its numbers to explode.
The adults are generally 2-inch-wide, orange moths, with a black band through the center of their wings. The larvae are usually yellow to dark green with gold heads. As they approach maturity, most caterpillars develop longitudinal stripes that extend down their bodies.
Some of the most important signs of looper infestations include damaged leaves and scarred fruit. Most avocado trees will tolerate low-level outbreaks, but when the insects occur in high numbers, the damage caused can be significant.
5. Orange Tortrix
The orange tortrix typically prefers feeding on grape vines, but they’ll also attack avocado trees when presented with the opportunity. Because the damage they cause is often quite similar to that caused by leafrollers, it is important to properly identify these insects before beginning a treatment regimen.
Adult life stages are generally about ½ inch long, orange to brown in color, and they often bear a diffuse V-shaped marking on their wings. Meanwhile, the larvae are typically straw-colored with tan heads. Multiple life stages are usually observed on the same tree at the same time.
The orange tortrix caterpillar primarily feeds on the leaves of avocado trees, but they’ll also damage fruit stems in some cases. You may also observe rolled-up leaves, which the insects use during their pupal stage.
6. Avocado Lace Bug
The avocado lace bug is a tiny pest of avocado trees that generally measures about 2 millimeters in length. The adults bear small, lacey wings that extend rearward, while the younger nymphs lack wings entirely.
These insects often go unnoticed by those who don’t carefully examine their trees. They’re usually easiest to spot by looking at the underside of your tree’s leaves, where they’ll appear like tiny black spots.
Avocado lace bugs cause harm to avocado trees via their piercing-sucking mouthparts, which they use to access the sugar-rich fluids contained inside the trees’ leaves. Light infestations are unlikely to seriously stress avocado trees, but heavy infestations can cause large-scale damage to the foliage, and thereby expose the tree to opportunistic pathogens.
If you suspect that your avocado trees are suffering from insect infestations, give your friends at Evergreen Arborist Consultants a call. We’ll have one of our experienced arborists inspect your trees, confirm the identity of the pests and recommend a prudent management strategy.