- Author: Mackenzie Patton
Eucalypt trees have become abundant in the California landscape, but so have the many invasive eucalypt pests that have arrived in California in the last couple decades.
In the fall of 2022, yet another invasive pest was added to the hoard of beetles, psyllids, and gall wasps that attack eucalypt trees. The dotted paropsine leaf beetle (Paraopsis atomaria) was found on a lemon scented gum tree (Corymbia citriodora) in Los Angeles County. It was the first report of the dotted paropsine leaf beetle in North America, and it has since become more problematic throughout Southern California. Currently the extent of the spread is unknown.
Like eucalypt trees, the dotted paropsine leaf beetle is native to Australia, where it is known as an abundant pest of at least twenty Eucalyptus and Corymbia species. Some of these tree species are commonly found in California, including the red gum (E. camaldulensis), rose gum (E. grandis), sugar gum (E. cladocalyx), and the silver-dollar gum (E. polyanthemos).
What does it look like?
Adult beetles are about 3/8 of an inch with oval bodies and little beady black eyes (Figure 1). They are tan in color and covered in orangish dots. There are darker spots along the top and edges of the wings. The antennae are straight and become slightly darker toward the tip.
Eggs are laid in a circular cluster around young stems and leaves. They are tan, cylindrical, and are laid in clusters of 20 – 100 eggs. The larvae of the dotted paropsine leaf beetle are yellowish in color with black heads and black ends (Figure 2). As they age, they develop black stripes along the top and sides. When larvae are threatened, they will raise their black back end. They will drop to the ground to pupate.
Damage and Solutions
Although small, the dotted paropsine leaf beetle and its larvae can cause significant damage to the leaves of a host tree. If they do not eat the whole leaf, they will leave behind distinct notches in the leaves like other eucalyptus leaf beetles. Severe infestations can cause defoliation and eventual death in stressed or young trees.
You can protect Eucalyptus or Corymbia species against insect infestations by providing proper horticultural care. Reducing any water or other environmental stressors will allow the tree to successfully fight off insect infestations.
If you are removing a eucalypt tree or dealing with a severe infestation, consider replanting with a California native or other tree that will not be susceptible to the dotted paropsine leaf beetle and other eucalypt pest.
Contact your local agricultural commissioner if you suspect you've found this beetle. For more information, please visit the LA County fact sheet regarding the dotted paropsine leaf beetle.
- Author: Mackenzie Patton
- Posted by: Gale Perez
The Invasive Pest Spotlight focuses on relevant or emerging invasive species in California. In this issue we are covering brooms, a group of invasive shrubs.
Brooms are upright shrubs in the legume family that typically produce small, yellow, pea-shaped flowers. Shrubs range from 3 to 10 feet tall. They produce flowers from mid spring to summer and produce seed pods in late summer. All brooms are prolific seed producers, with a single shrub producing as many as 2,000 to 3,500 pods containing up to 20,000 seeds.
While brooms are attractive plants, they grow in dense stands that outcompete many native plants. These dense stands are highly flammable and increase the risk of wildfires. The most common species found in California are Scotch broom, French broom, Spanish broom, and Portuguese broom. Scotch broom is often found on interior mountains and on lower slopes in Northern California and is very prevalent in the Sierra Nevada foothills. Without management, these plants can survive for about 12 to 17 years, producing thousands of seeds.
Actions You Can Take
First, avoid planting any broom species. While most retailers do not sell the most common invasive brooms, many do sell hybrids that could become highly invasive in the natural landscape. There are similar-looking alternatives to brooms, such as forsythia and golden currant. Contact your local UC Master Gardeners or visit PlantRight.org for a list of other alternatives.
If you have brooms on your property and want to remove them, there are many different nonchemical and chemical methods that are effective in controlling these plants. These options are extensively detailed in the UC IPM publication Pest Notes: Brooms.
Original source: UC IPM's Home & Garden Pest Newsletter Summer 2023 issue
- Author: Mackenzie Patton
The Invasive Pest Spotlight focuses on relevant or emerging invasive species in California. In this issue we are covering brooms, a group of invasive shrubs.
Invasive Broom facts
Brooms are upright shrubs in the legume family that typically produce small, yellow, pea-shaped flowers. Shrubs range from 3 to 10 feet tall. They produce flowers from mid spring to summer and produce seed pods in late summer. All brooms are prolific seed producers, with a single shrub producing as many as 2,000 to 3,500 pods containing up to 20,000 seeds.
While brooms are attractive plants, they grow in dense stands that outcompete many native plants. These dense stands are highly flammable and increase the risk of wildfires. The most common species found in California are Scotch broom, French broom, Spanish broom, and Portuguese broom. Scotch broom is often found on interior mountains and on lower slopes in Northern California and is very prevalent in the Sierra Nevada foothills. Without management, these plants can survive for about 12 to 17 years, producing thousands of seeds.
Actions you Can Take
First, avoid planting any broom species. While most retailers do not sell the most common invasive brooms, many do sell hybrids that could become highly invasive in the natural landscape. There are similar-looking alternatives to brooms, such as forsythia and golden currant. Contact your local UC Master Gardeners or visit PlantRight.org for a list of other alternatives.
If you have brooms on your property and want to remove them, there are many different nonchemical and chemical methods that are effective in controlling these plants. These options are extensively detailed in the UC IPM publication Pest Notes: Brooms.
[Originally featured in the Summer 2023 issue of UC IPM's Home & Garden Pest Newsletter]
They may seem too tiny to do much damage to a mature, healthy tree, but invasive shothole borers (ISHB) are responsible for the deaths of tens of thousands of trees in Southern California. These beetles bore into trees and infect them with Fusarium dieback, a fungal disease that kills the trees. Many native California trees like California sycamore, valley oak, and arroyo willow can be killed when invasive shothole borers attack them.
While these pests are currently only found in Southern California, they could spread to many other parts of the state. Limiting the infestation will reduce their impact. Controlling the beetles is difficult but includes regular monitoring of trees to quickly identify sources of beetles, disposing of infested cut wood, and appropriate pesticide treatments.
What can you do to help?
- Don't move firewood around the state. These beetles and other potentially damaging beetles are easily moved on cut wood. Buy it where you burn it.
- Learn more about host trees, symptoms of infestation, and what to do.
UC IPM's new publication, Pest Notes: Invasive Shothole Borers is written by various state experts on this pest and contains everything you need to know about the beetle. Visit the UC IPM website for specific management recommendations, identification of the beetles, and lists of trees affected.
- Editor: Jennifer Hopkins
Invasive Spotlight: Goldspotted Oak Borer (GSOB)
Adult goldspotted oak borer, Agrilus auroguttatus, on an oak leaf. Photo by Mike Lewis, Center for Invasive Species Research, Bugwood.org
There are several flatheaded boring beetles in California, however only a few are of particular concern. The goldspotted oak borer (GSOB), Agrilus auroguttatus, is a metallic wood-boring beetle that threatens our native trees. Since it was introduced to Southern California on contaminated firewood in the early 2000s, this pest has caused extensive damage to woodlands and native oaks.
What does the goldspotted oak borer look like?
Adult GSOB are 0.4 inch long and 0.08 inch wide with bullet-shaped bodies. They are black with an iridescent green sheen and six distinct gold spots on their back.
What damage does the goldspotted oak borer cause?
Goldspotted oak borers only attack oaks (Quercus spp.). They are particularly damaging to coast live oak and California black oak. Adult beetles lay eggs on host trees and the larvae bore into the wood, feeding on the tree's vascular tissue. The larvae feed on the tree until they pupate into adults and exit the tree, leaving D-shaped exit holes in the bark. Extensive GSOB feeding can girdle trees, disrupting water and nutrient uptake and eventually causing the tree to die.
What can you do about the goldspotted oak borer?
Don't move firewood! The most important way to prevent the spread of invasive wood borers like GSOB, is to buy firewood where you're going to burn it. If you live in an area of Southern California where GSOB is present, avoid planting susceptible trees. If you need to remove an infested tree, keep the cut wood away from healthy oaks and tarp or grind the wood to kill any larvae present. To report possible sightings, fill out the Goldspotted Oak Borer Symptoms Reporting Form at https://ucanr.edu/sites/gsobinfo/What_You_Can_Do/Report_GSOB_Symptoms/
To learn more about this invasive pest visit the UC IPM Pest Notes: Goldspotted Oak Borer or the UC ANR Goldspotted Oak Borer page.
