Dotted Paropsine Beetles in LA and Orange County
- gregorycmink
- Jul 28, 2024
- 4 min read
Imagine this: you walk out to your patio to enjoy a coffee on a beautiful warm Southern California morning. You pull the chair out and notice brown and green crumbs staining the upholstery and piling up on the table. It mostly brushes off easily, mostly. Some of it is wet and rubs into the chair cushion. “I’ll clean that up later”. You pick up a book and notice a weird black and yellow grub crawling on the cover. You quickly flick it away. You pick up your coffee cup to take a sip but see several black specks floating on its surface (spoiler alert: it’s beetle poop). A pink beetle clumsily flies around the cup and lands on its rim. It is the same shape as a ladybug, but much bigger. In a panic, you jump out of the chair and spin around. You finally realize there are hundreds of these yellow grubs and pink beetles on the table, the patio, your chair, and all landscape plants. You raise your gaze to the eucalyptus with your mouth slightly agape and notice the leaves look tattered. A steady drop of small pellets bounces off your face as you think, “Am I in a horror movie? “
The answer is: YES
The Dotted Paropsine Beetle (Paropsis atomaria) was first detected in LA County in August 2022. https://file.lacounty.gov/SDSInter/acwm/1134554_Dottedparopsine.pdf
It has since spread throughout LA and Orange County, attacking many different types of eucalyptus trees. There are dozens of species of Eucalyptus and Corymbia throughout our area, but this beetle really seems to love Red Ironbark, River Red Gum, Silver Dollar Gum, Blue Gum, Sugar Gum, and Lemon Scented Gum. However, this beetle can be found on every species of Eucalyptus I’m aware of in our area. When a pest finds a new territory to colonize, it can sometimes undergo tremendous population growth because of a lack of predators or host adaptations. Right now, this invasive beetle is taking advantage of southern California’s mild climate and lack of interested predators to expand unchecked.
These are different sizes of larvae:
And here is what the adult and the egg cases look like:
There are two problems caused the Dotted Paropsine Beetle:
1. Damage to the tree- The larvae feed on the leaves. As the larvae grow, their mouths cause greater damage to the leaves. Damage progresses from an abrasion on one side of the leaves to notches along the edges to complete removal. Trees depend on their leaves to create food. A healthy tree can tolerate being defoliated once or twice, but really runs into problems if it is defoliated constantly. The tree will continue to expend its energy reserves to make new leaves, but will not reap any benefit of that investment before the beetle larvae eat the emerging leaves. An unhealthy tree is much less tolerant of defoliation. Many eucalyptus trees have been in poor condition due to underwatering or attacks by other invasive pests. This new beetle can be the “nail in the coffin” for your tree.
2. Reducing the enjoyment of your yard- it’s hard to enjoy a space with beetle poop raining down on you. These are voracious feeders who colonize the entire canopy of a tree, leaving everything below the tree covered in excrement. While the shade of a tree can create a very enjoyable yard, it is not so enjoyable if that canopy harbors thousands of larvae who effortlessly convert leaves to poop.
So what are the solutions? Many invasive pests experience a population outbreak when they colonize a suitable area with no predator pressure. At some point, a non-native predator will take hold in the area because of the prevalence of the pest/prey, or native predators will realize the Paropsis beetle is good eating. This is known as BIOLOGICAL control and is the cheapest (free) and sustainable solution for the problem. Until a predator species takes hold, we rely on CHEMICAL control to protect high-value or high-risk trees. I view chemical control as an emergency measure to bridge the gap until biological control can make a serious impact on the pest.
If you have a eucalyptus tree (some species are more commonly called Gum trees) and notice damage from these insects, I can provide systemic insecticide treatments to reduce their population on a given tree. These treatments are injected into the soil near the tree or into the trunk itself and translocated by the tree to its leaves. This is the most environmentally safe and effective way to get control. The treatments cannot give 100% control because of the thousands of untreated trees in the area serving as host to these insects. However, a severe reduction in beetle population can make your patio usable again and possibly prevent your tree from dying from constant, complete defoliation. The treatments only need to happen until biological control takes hold in the area.
WHAT TO DO:
If you send me your address and the circumference of the tree, I can provide a quote for systemic treatments for this pest.
Use a flexible tape measure (like a tailor’s measuring tape) to measure the circumference of the tree 4.5’ above ground level. I will convert this circumference to the diameter. This measurement is the “Diameter at Breast Height” and is the basis for determining how much chemical the tree will need.
Use the Contact Me tab to fill out an online inquiry. Include pictures of your trees, the property address, and the circumference of the trees and I will respond with a quote